Using an arrow function to assign a value to a variable

Question

Using an arrow function to assign a value to a variable

I have a quick question as I'm still learning arrow functions. I understand that they implicitly return, and we can use implicit returns with expressions. However, my question is about the following scenario:

$scope.setEdit = () => { $scope.edit = true; }

Can I simplify it to

$scope.setEdit = () => $scope.edit = true;

without any unexpected side effects? I'm not sure how arrow functions behave when used for simple variable assignments. So far, I have only used them in places where I would normally include a return statement, not for simple assignments.

This example is just to illustrate my question. Thank you!

javascript angularjs ecmascript-6 arrow-functions

Answer 1

Answer №1

While arrow functions are often associated with concise syntax, the key point here is how expressions are evaluated within these functions. The final result of the expression, along with any potential side effects, will determine the returned value.

Consider the following arrow-expression function:

() => a = b

This function actually behaves and returns the same as:

() => {
    return a = b;
}

Essentially, this is a function that modifies variables (side effects) as it runs: a receives the value of b. In JavaScript, assignments can be made within expressions and the assigned value can be returned. Therefore, the initial function is essentially equivalent to:

() => {
    a = b;
    return b;
}

Answer 2

While arrow functions are often associated with concise syntax, the key point here is how expressions are evaluated within these functions. The final result of the expression, along with any potential side effects, will determine the returned value.

Consider the following arrow-expression function:

() => a = b

This function actually behaves and returns the same as:

() => {
    return a = b;
}

Essentially, this is a function that modifies variables (side effects) as it runs: a receives the value of b. In JavaScript, assignments can be made within expressions and the assigned value can be returned. Therefore, the initial function is essentially equivalent to:

() => {
    a = b;
    return b;
}

Answer 3

Answer №2

I believe there might be a misconception about how arrow functions operate. They only automatically return values when you use the concise syntax.

Let me illustrate - these three functions are essentially the same, all returning the string 'hello'

function a() { return 'hello' }
const b = () => { return 'hello' }; //arrow function with braces requires explicit return statement
const c = () => 'hello';            //shorthand arrow function without braces implicitly returns value

Here's an example demonstrating this concept using different function styles

//regular function with no return value
var a = 'bar';
const myFunc1 = function() { a = 'foo'; }
console.log(myFunc1(), a);

//regular function with a return value
a = 'bar';
const myFunc2 = function() { return a = 'foo'; }
console.log(myFunc2(), a);

//arrow function with a return value
a = 'bar';
const myFunc3 = () => { return b = 'foo'; }
console.log(myFunc3(), a);

//arrow function with no return value
a = 'bar';
const myFunc4 = () => { b = 'foo'; }
console.log(myFunc4(), a);

//arrow function using shorthand, which has an implicit return value
a = 'bar';
const myFunc5 = () => b = 'foo';
console.log(myFunc5(), a);

Answer 4

I believe there might be a misconception about how arrow functions operate. They only automatically return values when you use the concise syntax.

Let me illustrate - these three functions are essentially the same, all returning the string 'hello'

function a() { return 'hello' }
const b = () => { return 'hello' }; //arrow function with braces requires explicit return statement
const c = () => 'hello';            //shorthand arrow function without braces implicitly returns value

Here's an example demonstrating this concept using different function styles

//regular function with no return value
var a = 'bar';
const myFunc1 = function() { a = 'foo'; }
console.log(myFunc1(), a);

//regular function with a return value
a = 'bar';
const myFunc2 = function() { return a = 'foo'; }
console.log(myFunc2(), a);

//arrow function with a return value
a = 'bar';
const myFunc3 = () => { return b = 'foo'; }
console.log(myFunc3(), a);

//arrow function with no return value
a = 'bar';
const myFunc4 = () => { b = 'foo'; }
console.log(myFunc4(), a);

//arrow function using shorthand, which has an implicit return value
a = 'bar';
const myFunc5 = () => b = 'foo';
console.log(myFunc5(), a);

Answer 5

Answer №3

When it comes to programming, an assignment can be likened to just another expression:

  const a = () => b = 1;

  console.log(
    c = 1,
    a()
  );

Is it possible to execute this without any unexpected outcomes?

Whether or not there will be issues depends on whether the caller anticipates a return value. If not, the result of the function call will essentially vanish into thin air, rendering it inconsequential.

Answer 6

When it comes to programming, an assignment can be likened to just another expression:

  const a = () => b = 1;

  console.log(
    c = 1,
    a()
  );

Is it possible to execute this without any unexpected outcomes?

Whether or not there will be issues depends on whether the caller anticipates a return value. If not, the result of the function call will essentially vanish into thin air, rendering it inconsequential.

Using an arrow function to assign a value to a variable

Answer №1

Answer №2

Answer №3

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