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How to Assign to the Property of a Function Parameter in JavaScript

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Assignment to Property of Function Parameter

One of the most powerful features of JavaScript is the ability to assign values to the properties of function parameters. This can be used to create complex and dynamic code that can be easily modified.

In this article, we will take a closer look at assignment to property of function parameter. We will discuss what it is, how it works, and how it can be used to improve your code.

We will also provide some examples of how assignment to property of function parameter can be used in practice. By the end of this article, you will have a solid understanding of this important JavaScript concept.

In JavaScript, a function parameter is a variable that is declared inside the function’s parentheses. When a function is called, the value of the argument passed to the function is assigned to the function parameter.

For example, the following function takes a string argument and prints it to the console:

js function greet(name) { console.log(`Hello, ${name}`); }

greet(“world”); // prints “Hello, world”

In this example, the `name` parameter is assigned the value of the `”world”` argument.

Assignment to property of function parameter

Assignment to property of function parameter is a JavaScript feature that allows you to assign a value to a property of a function parameter. This can be useful for initializing the value of a parameter or for passing a reference to an object.

For example, the following code assigns the value `”hello”` to the `name` property of the `greet` function parameter:

js function greet(name) { name.value = “hello”; }

greet({ value: “world” }); // prints “hello”

In this example, the `name` parameter is a JavaScript object. The `value` property of the `name` object is assigned the value of the `”hello”` argument.

When to use assignment to property of function parameter?

You should use assignment to property of function parameter when you need to:

  • Initialize the value of a parameter
  • Pass a reference to an object

Avoid creating a new object

Initializing the value of a parameter

You can use assignment to property of function parameter to initialize the value of a parameter. For example, the following code initializes the `name` property of the `greet` function parameter to the value of the `”world”` argument:

js function greet(name) { name.value = “world”; }

Passing a reference to an object

You can use assignment to property of function parameter to pass a reference to an object. For example, the following code passes a reference to the `person` object to the `greet` function:

js function greet(person) { console.log(`Hello, ${person.name}`); }

const person = { name: “John Doe” };

greet(person); // prints “Hello, John Doe”

You can use assignment to property of function parameter to avoid creating a new object. For example, the following code uses assignment to property of function parameter to avoid creating a new object for the `name` parameter:

greet(“John Doe”); // prints “Hello, John Doe”

In this example, the `name` parameter is a string literal. The `name` property of the `name` parameter is assigned the value of the `”John Doe”` string literal. This avoids creating a new object for the `name` parameter.

Assignment to property of function parameter is a JavaScript feature that can be used to initialize the value of a parameter, pass a reference to an object, and avoid creating a new object. It is a powerful feature that can be used to improve the performance and readability of your code.

Additional resources

  • [MDN: Assignment to property of function parameter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Assignment_to_property_of_function_parameter)
  • [Stack Overflow: When to use assignment to property of function parameter?](https://stackoverflow.com/questions/1435573/when-to-use-assignment-to-property-of-function-parameter)
  • [Codecademy: Assignment to property of function parameter](https://www.codecademy.com/learn/javascript/lessons/assignment-to-property-of-function-parameter)

3. How to use assignment to property of function parameter?

To use assignment to property of function parameter, you can simply assign a value to the property of the function parameter. For example, the following code assigns the value `”hello”` to the `name` property of the `greet` function parameter:

In this example, the `greet` function is called with the argument `”world”`. The `name` property of the `greet` function parameter is then assigned the value `”hello”`. When the `greet` function is called, the value of the `name` property is used to print the message `”Hello, world”`.

Assignment to property of function parameter can be used to initialize the value of a parameter, pass a reference to an object, or avoid creating a new object.

You can use assignment to property of function parameter to initialize the value of a parameter. For example, the following code initializes the value of the `name` property of the `greet` function parameter to the value of the `name` variable:

js function greet(name) { name = “world”; console.log(`Hello, ${name}`); }

In this example, the `name` variable is assigned the value `”world”` before the `greet` function is called. The `name` property of the `greet` function parameter is then assigned the value of the `name` variable. When the `greet` function is called, the value of the `name` property is used to print the message `”Hello, world”`.

You can use assignment to property of function parameter to pass a reference to an object. For example, the following code passes a reference to the `user` object to the `greet` function:

js function greet(user) { console.log(`Hello, ${user.name}`); }

const user = { name: “John Doe”, };

greet(user); // prints “Hello, John Doe”

In this example, the `user` object is passed to the `greet` function as a parameter. The `greet` function then uses the `name` property of the `user` object to print the message `”Hello, John Doe”`.

Avoiding creating a new object

You can use assignment to property of function parameter to avoid creating a new object. For example, the following code uses assignment to property of function parameter to avoid creating a new object for the `user` variable:

In this example, the `user` variable is assigned the value of the `user` object. The `greet` function then uses the `name` property of the `user` variable to print the message `”Hello, John Doe”`.

By using assignment to property of function parameter, you can avoid creating a new object for the `user` variable. This can improve the performance of your code and reduce the amount of memory that is used.

4. Pitfalls of assignment to property of function parameter

There are a few pitfalls to be aware of when using assignment to property of function parameter:

  • The value of the property may be overwritten. If you assign a value to the property of a function parameter, the value of the property may be overwritten by the next time the function is called. For example, the following code assigns the value `”hello”` to the `name` property of the `greet` function parameter. The next time the `greet` function is called, the value of the `name` property will be overwritten by the value of the `name` argument.

js function greet(name) { name = “hello”; console.log(`Hello, ${name}`); }

greet(“world”); // prints “Hello, hello” greet(“hello”); // prints “Hello, hello”

A: Assignment to property of function parameter occurs when you assign a value to a property of a function parameter. This can be done by using the dot operator (.) to access the property, or by using the bracket operator ([]) to index into the property.

For example, the following code assigns the value “10” to the `x` property of the `foo()` function’s parameter `y`:

const foo = (y) => { y.x = 10; };

foo({ x: 5 }); // { x: 10 }

Q: Why is assignment to property of function parameter dangerous?

A: Assignment to property of function parameter can be dangerous because it can change the value of the property in the calling scope. This can lead to unexpected behavior and errors.

For example, the following code changes the value of the `x` property of the global variable `a`:

foo({ x: 5 }); // a.x is now 10

This behavior can be difficult to debug, as it may not be obvious that the change to the `x` property is being caused by the `foo()` function.

Q: How can I avoid assignment to property of function parameter?

There are a few ways to avoid assignment to property of function parameter. One way is to use the `const` keyword to declare the function parameter as a constant. This will prevent the value of the parameter from being changed.

Another way to avoid assignment to property of function parameter is to use the `readonly` keyword to declare the function parameter as read-only. This will prevent the value of the parameter from being changed, even by assignment to a property of the parameter.

Finally, you can also use the `Object.freeze()` method to freeze the object that is passed as the function parameter. This will prevent any changes to the object, including changes to the values of its properties.

Q: What are the best practices for assignment to property of function parameter?

The best practices for assignment to property of function parameter are as follows:

  • Use the `const` keyword to declare function parameters as constants.
  • Use the `readonly` keyword to declare function parameters as read-only.
  • Use the `Object.freeze()` method to freeze objects that are passed as function parameters.

Here are some key takeaways from this article:

  • Assigning to the property of a function parameter can change the value of the original variable.
  • This can lead to unexpected behavior and security vulnerabilities.
  • To avoid this problem, use the `const` keyword or pass arguments by reference.

By following these tips, you can write more secure and reliable JavaScript code.

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  • Assignment to property of function parameter no-param-reassign

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Last updated: May 9, 2023 Reading time · 3 min

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# Table of Contents

  • Disabling the no-param-reassign ESLint rule for a single line
  • Disabling the no-param-reassign ESLint rule for an entire file
  • Disabling the no-param-reassign ESLint rule globally

# Assignment to property of function parameter no-param-reassign

The ESLint error "Assignment to property of function parameter 'X' eslint no-param-reassign" occurs when you try to assign a property to a function parameter.

To solve the error, disable the ESLint rule or create a new object based on the parameter to which you can assign properties.

assignment to property of function parameter eslint no param reassign

Here is an example of how the error occurs.

The ESLint rule forbids assignment to function parameters because modifying a function's parameters also mutates the arguments object and can lead to confusing behavior.

One way to resolve the issue is to create a new object to which you can assign properties.

We used the spread syntax (...) to unpack the properties of the function parameter into a new object to which we can assign properties.

If you need to unpack an array, use the following syntax instead.

The same approach can be used if you simply need to assign the function parameter to a variable so you can mutate it.

We declared the bar variable using the let keyword and set it to the value of the foo parameter.

We are then able to reassign the bar variable without any issues.

# Disabling the no-param-reassign ESLint rule for a single line

You can use a comment if you want to disable the no-param-reassign ESLint rule for a single line.

Make sure to add the comment directly above the assignment that causes the error.

# Disabling the no-param-reassign ESLint rule for an entire file

You can also use a comment to disable the no-param-reassign ESLint rule for an entire file.

Make sure to add the comment at the top of the file or at least above the function in which you reassign parameters.

The same approach can be used to disable the rule only for a single function.

The first comment disables the no-param-reassign rule and the second comment enables it.

If you try to reassign a parameter after the second comment, you would get an ESLint error.

# Disabling the no-param-reassign ESLint rule globally

If you need to disable the no-param-reassign rule globally, you have to edit your .eslintrc.js file.

disable no param reassign rule globally

If you only want to be able to assign properties to an object parameter, set props to false instead of disabling the rule completely.

The following code is valid after making the change.

If you use a .eslintrc or .eslintrc.json file, make sure to double-quote the properties and values.

If you want to only allow assignment to object parameters, use the following line instead.

Make sure all properties are double-quoted and there are no trailing commas if your config is written in JSON.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

  • eslint is not recognized as an internal or external command
  • Plugin "react" was conflicted between package.json » eslint-config-react-app
  • React: Unexpected use of 'X' no-restricted-globals in ESLint
  • TypeScript ESLint: Unsafe assignment of an any value [Fix]
  • ESLint error Unary operator '++' used no-plusplus [Solved]
  • ESLint Prefer default export import/prefer-default-export
  • Arrow function should not return assignment. eslint no-return-assign
  • TypeError: Cannot redefine property: X in JavaScript [Fixed]
  • ESLint: disable multiple rules or a rule for multiple lines
  • Expected linebreaks to be 'LF' but found 'CRLF' linebreak-style
  • Missing return type on function TypeScript ESLint error

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no-param-reassign

Disallow reassigning function parameters

Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments object when not in strict mode (see When Not To Use It below). Often, assignment to function parameters is unintended and indicative of a mistake or programmer error.

This rule can be also configured to fail when function parameters are modified. Side effects on parameters can cause counter-intuitive execution flow and make errors difficult to track down.

Rule Details

This rule aims to prevent unintended behavior caused by modification or reassignment of function parameters.

Examples of incorrect code for this rule:

Examples of correct code for this rule:

This rule takes one option, an object, with a boolean property "props" , and arrays "ignorePropertyModificationsFor" and "ignorePropertyModificationsForRegex" . "props" is false by default. If "props" is set to true , this rule warns against the modification of parameter properties unless they’re included in "ignorePropertyModificationsFor" or "ignorePropertyModificationsForRegex" , which is an empty array by default.

Examples of correct code for the default { "props": false } option:

Examples of incorrect code for the { "props": true } option:

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsFor" set:

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsForRegex" set:

When Not To Use It

If you want to allow assignment to function parameters, then you can safely disable this rule.

Strict mode code doesn’t sync indices of the arguments object with each parameter binding. Therefore, this rule is not necessary to protect against arguments object mutation in ESM modules or other strict mode functions.

This rule was introduced in ESLint v0.18.0.

Further Reading

Avatar image for spin.atomicobject.com

  • Rule source
  • Tests source

Disallow Reassignment of Function Parameters (no-param-reassign)

Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments object. Often, assignment to function parameters is unintended and indicative of a mistake or programmer error.

This rule can be also configured to fail when function parameters are modified. Side effects on parameters can cause counter-intuitive execution flow and make errors difficult to track down.

Rule Details

This rule aims to prevent unintended behavior caused by modification or reassignment of function parameters.

Examples of incorrect code for this rule:

Examples of correct code for this rule:

This rule takes one option, an object, with a boolean property "props" , and arrays "ignorePropertyModificationsFor" and "ignorePropertyModificationsForRegex" . "props" is false by default. If "props" is set to true , this rule warns against the modification of parameter properties unless they're included in "ignorePropertyModificationsFor" or "ignorePropertyModificationsForRegex" , which is an empty array by default.

Examples of correct code for the default { "props": false } option:

Examples of incorrect code for the { "props": true } option:

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsFor" set:

Examples of correct code for the { "props": true } option with "ignorePropertyModificationsForRegex" set:

When Not To Use It

If you want to allow assignment to function parameters, then you can safely disable this rule.

Further Reading

  • JavaScript: Don’t Reassign Your Function Arguments

This rule was introduced in ESLint 0.18.0.

  • Rule source
  • Documentation source

© OpenJS Foundation and other contributors Licensed under the MIT License. https://eslint.org/docs/rules/no-param-reassign

Disallow Reassignment of Function Parameters (no-param-reassign)

Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments object. Often, assignment to function parameters is unintended and indicative of a mistake or programmer error.

This rule can be also configured to fail when function parameters are modified. Side effects on parameters can cause counter-intuitive execution flow and make errors difficult to track down.

Rule Details

This rule aims to prevent unintended behavior caused by modification or reassignment of function parameters.

Examples of incorrect code for this rule:

Examples of correct code for this rule:

This rule takes one option, an object, with a boolean property "props" and an array "ignorePropertyModificationsFor" . "props" is false by default. If "props" is set to true , this rule warns against the modification of parameter properties unless they’re included in "ignorePropertyModificationsFor" , which is an empty array by default.

Examples of correct code for the default { "props" : false } option:

Examples of incorrect code for the { "props" : true } option:

Examples of correct code for the { "props" : true } option with "ignorePropertyModificationsFor" set:

When Not To Use It

If you want to allow assignment to function parameters, then you can safely disable this rule.

Further Reading

  • JavaScript: Don’t Reassign Your Function Arguments

This rule was introduced in ESLint 0.18.0.

  • Rule source
  • Documentation source

JavaScript: Don’t Reassign Your Function Arguments

UPDATE : The point of this post is to raise awareness that reassigning the value of an argument variable mutates the arguments object. The code example is contrived and exists solely to help illustrate that behavior.

Did you know that a JavaScript function’s named parameter variables are synonyms for the corresponding elements in that function’s Arguments object?

I ran into this while experimenting with a function that was written to take either two or three arguments, providing a default for the first argument if only two are passed.

Strangely, all of the values in the result object are set to "green" . I was expecting to see

But when I set favoriteColor to "green" I was also changing arguments[0] to be "green" . The situation only got worse when I set name = arguments[0] effectively changing arguments[1] to be "green" as well.

I had not realized that named arguments are synonyms for the elements of the Arguments object. I found a good explanation on Rx4AJAX:

The numbered properties of the Arguments Object are synonymous with the local variables that hold the named function parameters. They both reference the same address in the stack. If the function body has code that changes the value of a parameter either via a name reference or the arguments[] array reference, both referenced values will reflect the same value.

Regardless of the language, it is generally not a good idea to reassign the parameter variables inside a function. In JavaScript it turns out to be a really bad idea.

Additional information:

  • Check out this jsFiddle to experiment with the code snippet above.
  • A comment on this StackOverflow question describes this “magical behavior” of JavaScript.
  • JavaScript Garden describes this behavior in its section on the arguments object.

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So the arguments object isn’t a “real” array, so you run into problems when you treat it as such.

Here’s a working example where you turn the arguments object into an array with Array.prototype.slice()

http://jsfiddle.net/wookiehangover/yZPj8/4/

This is a pretty common beginner’s mistake and is covered in most advanced books, such as Javascript Patterns or High Performance Javascript.

Here’s a good resource about how the arguments object works: https://developer.mozilla.org/en/JavaScript/Reference/functions_and_function_scope/arguments

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If you slice the Arguments, the get aan array, which is not “live”. This way, you can reassign the arguments without any problems. http://jsfiddle.net/Avorin/yZPj8/6/

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When I want to pass a varying number of parameters to a function, I either use a predefined object or an object literal myself to begin with (I presume this example function is simplified).

You can also clutter up the function calls with things like makePerson(null, “Joe”, 18) and test for nulls, too, instead of array lengths.

This is the solution I found, using this. instead of an args array. I’m not sure which solution is better.

http://jsfiddle.net/Q2LMT/

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Or simply refer to the arguments by name when changing their values.

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This article roughly says:

When you misuse the arguments object, unexpected results happen.

The solution: don’t misuse the arguments object. Leave the param list empty and use your logic to fill out variable names if you need that

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This is why I love working with Rails… most Rails functions take hashes as arguments, so you can your real arguments in in any order, and it guarantees code verbosity. Example:

button_to ‘Add to Cart’, line_items_path(:product_id => product), :remote => true

where :remote=>true is the third argument, a hash, and contains all optional parameters you could add (in this case, :method, :disabled, :confirm, and :remote).

' src=

var makePerson = function(favoriteColor, name, age) { if (arguments.length < 3) { favoriteColor = "green"; name = arguments[0]; age = arguments[1]; } return { name: name, age: age, favoriteColor: (arguments.length < 3 ? "green" : favoriteColor) }; };

' src=

How very Perl-ish of Javascript.

Ignore this blog post’s advice. It is perfectly fine to reassign function arguments in Javascript. If you just follow the convention of putting option arguments at the end of the argument list instead of the beginning, you avoid this problem all together and simplify your code:

var makePerson = function(name, age, favoriteColor) { favoriteColor = favoriteColor || “green”; return { name: name, age: age, favoriteColor: favoriteColor }; };

' src=

Who makes the first argument optional? Seriously? There are numerous things wrong with your code.

' src=

What a terrible programming language.

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Larry Clapp, this isn’t perlish at all. In Perl you do named parameters through local variables. They’re duplicated not ref-copied.

use strict; use warnings;

my $makePerson = sub { my ( $favoriteColor, $name, $age ) = @_;

if ( @_ $name , age => $age , favoriteColor => $favoriteColor }

use Data::Dumper; die Dumper $makePerson->(‘Joe’, 18);

What you’re confusing is Perl’s special array variable `@_` which is used to store references to the parameters from the caller, making them accessible in the callee. So the sub implementation themselves are pass-by-reference, but the assignment itself requires a total copy. Not to say you couldn’t achieve the same effect with Perl if you *really wanted too*, but it requires a ton of non-accidental (contrived) work.

my $makePerson = sub { my ( $favoriteColor, $name, $age ) = ( \$_[0], \$_[1], \$_[2] ); #my ( $favoriteColor, $name, $age ) = @_;

if ( length @_ $$name , age => $$age , favoriteColor => $$favoriteColor }

use Data::Dumper; my $name = ‘Joe’; my $age = 18; die Dumper $makePerson->($name, $age);

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How about just using a configuration object?

var person = makePerson({name:”Joe”, age:18})

Inside the function look for the property you want to default.

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JavaScript reveals more and more of its awful design. NaN != NaN ?????

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the problem isn’t with using arguments , the problem is with your use of it.

Writing the code: function example (x, y, z) { x = 1; y = arguments[0]; z = arguments[1]; }

will make every value 1 because I wasn’t very careful about the order of my actions.

As the article you quoted states, the variables x, y, and z are synonymous with arguments [0], [1], and [2] respectively, so if I called example(3,4) all I would be doing in my function is assigning 3 to x and 4 to y with the function call, then assigning 1 to x, the value of x to y, then the value of y to z. All of my values would be the same (and 1) afterwards.

You do the same thing in your code. You pass in (favoriteColor: Joe, name: 18) and then set the favoriteColor to “green” before taking the value of “green” and pasting it on to the name, then taking the new value of name (also “green”) and pasting it in to the value of age. If you had instead written that code in the reverse order, it would have worked as you had initially expected.

[…] service allows you to react immediately to spikes in website traffic. Just recently our blog had a post go viral on Reddit causing an extreme spike in traffic. Using a live information radiator on our office […]

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There are special edge cases like Array.prototype.reduce where assign to accumulator argument passed between iterations is only good practice:

const aggregate = someArray.reduce((acc, item) => { acc[item.prop] = (acc[item.prop] || 0) + 1; }, {} /* this is initial state */);

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Choose Parameters or Arguments….but using both is asking for trouble.

If you are using Parameters defined in the Function signature, then you have no need to refer to the arguments information.

If you plan on using arguments, then do not define Parameters.

Mixing the two, is asking for problems and the reason for the overall purpose of this post.

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How to avoid "Assignment to property of function parameter 'elem'" #1653

@darde

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freeCodeCamp Challenge Guide: Use Destructuring Assignment to Pass an Object as a Function's Parameters

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You could pass the entire object, and then pick the specific attributes you want by using the . operator. But ES6 offers a more elegant option!

Get rid of the stats , and see if you can destructure it. We need the max and min of stats .

Code Explanation

Notice that we are destructuring stats to pass two of its attributes - max and min - to the function. Don’t forget to the modify the second return statement. Change stats.max to just max , and change stats.min to just min .

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  4. Lec10/Relations/Properties of Relations/Example

  5. Discussion of Q4c A02 the FUNction TWICE with actual, formal, reference, and value parameters

  6. FUNCTIONS 3- Problems on Relations

COMMENTS

  1. Assignment to property of function parameter (no-param-reassign)

    This is a common ESLint issue that appears frequently on old codebase. You have modified the result variable which was passed as parameter. This behavior is prohibited by the rule. To resolve it, copy the argument to a temporary variable and work on it instead: export const fn = article => article.categoryValueDtoSet.reduce((res, item) => {.

  2. Assignment to property of function parameter 'a' Eslint

    To fix this error, either: disable the eslint rule (in your .eslintrc or just for the function) create new variables to avoid re-assigning to a and b (see below): sortingAlgo = (a, b) => {. // we need to use custom sorting algorithm to meet our requirements. const aPos = a.pos.toUpperCase();

  3. How to Assign to the Property of a Function Parameter in JavaScript

    Assignment to Property of Function Parameter. One of the most powerful features of JavaScript is the ability to assign values to the properties of function parameters. This can be used to create complex and dynamic code that can be easily modified. In this article, we will take a closer look at assignment to property of function parameter.

  4. Assignment to property of function parameter no-param-reassign

    function createEmployee(emp) { // ⛔️ Assignment to property of function parameter 'emp'. eslint no-param-reassign. emp.name = 'bobby hadz'; emp.salary = 500; return emp; } The ESLint rule forbids assignment to function parameters because modifying a function's parameters also mutates the arguments object and can lead to confusing behavior.

  5. no-param-reassign

    If you want to allow assignment to function parameters, then you can safely disable this rule. Strict mode code doesn't sync indices of the arguments object with each parameter binding. Therefore, this rule is not necessary to protect against arguments object mutation in ESM modules or other strict mode functions. Version

  6. no-param-reassign

    Licensed under the MIT License. Disallow Reassignment of Function Parameters (no-param-reassign) Assignment to variables declared as function parameters can be misleading and lead to confusing behavior, as modifying function parameters will also mutate the arguments object. Often, assignment to function parameters is unintended and indicative ...

  7. no-param-reassign

    Options. This rule takes one option, an object, with a boolean property "props" and an array "ignorePropertyModificationsFor"."props" is false by default. If "props" is set to true, this rule warns against the modification of parameter properties unless they're included in "ignorePropertyModificationsFor", which is an empty array by default.. props ...

  8. TypeScript Reactjs: Assignment to property of function parameter 'state

    Hello I have a problem in my estlint: Assignment to property of function parameter 'state'. eslintno-param-reassign on this code: state.sideisOpen = action.payload; interface SideBar { sideisOpen: boolean; } const INITIAL_STATE: SideBar ...

  9. Code Inspection: Assignment to function parameter

    Code Inspection: Assignment to function parameter. Reports an assignment to a function parameter, including increment and decrement operations.

  10. Why assignment to property of function parameter is bad style

    no-param-reassign as "never reassign parameters" is ok. no-param-reassign as "never mutate parameters" means eslint-config-airbnb enforces immutability paradigm. It makes a profound design choice for us.

  11. Do we want to recommend the no-param-reassign eslint rule in ...

    I just had this idea when another user tried to assign to the state function argument. There is actually an eslint rule for that: no-param-reassign. I'd suggest we either add that rule as a recommendation somehwere in the docs or go even one step farther and create a shareable config package .. That way we could add some more recommended rules in the future.

  12. JavaScript: Don't Reassign Your Function Arguments

    They both reference the same address in the stack. If the function body has code that changes the value of a parameter either via a name reference or the arguments[] array reference, both referenced values will reflect the same value. Regardless of the language, it is generally not a good idea to reassign the parameter variables inside a function.

  13. Why eslint throws "Assignment to property of function parameter

    I started learning javascript a week ago. Started using eslint yesterday and it's very useful. I have been trying this part of the code for sometime now and eslint keeps throwing Assignment to property of function parameter 'element'. Here is the code;

  14. Why eslint throws "Assignment to property of function parameter

    I have been trying this part of the code for sometime now and eslint keeps throwing Assignment to property of function parameter 'element'.Here is the code; closeIcon.addEventListener('click', => { [homeClass, navBar].forEach((element) => { element.style.opacity = 1; element.style.pointerEvents = 'auto'; }); }); ... so for you second question ...

  15. object oriented

    Parameterizing vs property assignment. Today I had a dicussion with a colleague. I tend to believe that a value in a property should be a meaningful part of the state of an object at any given time. This automatically almost always makes the constructor fully responsible for the initial assignment of all the properties in a class.

  16. How to avoid the assignment to property of function parameter ...

    willshowell • 5 yr. ago. The point of that eslint rule is to avoid mutating function parameters. In general you probably want to prefer an immutable approach, which is what the rule recommends. However, mutating the request object is exactly how express middleware is supposed to be done. It looks like there are options you can pass to the ...

  17. How to avoid "Assignment to property of function parameter 'elem

    Hi guys, I want to understand how you guys avoid the eslint warning "Assignment to property of function parameter 'elem'". I know that is a good pattern do not change function parameters values. This keeps our code decoupled and with high maintenance. However, in some cases, I come across with the following situation.

  18. Assignment to function parameter 'value' no-param-reassign

    Assignment to property of function parameter (no-param-reassign) 2 ReactJS es-lint: Return statement should not contain assignment. 2 "Parsing error: Argument expression expected. eslint" with Typescript map function in React ... Please be sure to answer the question. Provide details and share your research!

  19. javascript

    The no-param-reassign warning makes sense for common functions, but for a classic Array.forEach loop over an array which you intend to mutate it isn't to appropriate. However, to get around this, you can also use Array.map with a new object (if you are like me, dislike snoozing warnings with comments): someArray = someArray.map((_item) => {.

  20. freeCodeCamp Challenge Guide: Use Destructuring Assignment to Pass an

    Use Destructuring Assignment to Pass an Object as a Function's Parameters Problem Explanation You could pass the entire object, and then pick the specific attributes you want by using the . operator. But ES6 offers a more elegant option! Hints Hint 1 Get rid of the stats, and see if you can destructure it. We need the max and min of stats.