# Logical Assignment Operators in JS

Logical assignment operators are a very new feature in JavaScript.  
Never heard of them? then this article is for you.    


There are three logical assignmet operators in JavaScript
1. Logical **OR** assignment operator (||=)
2. Logical **AND** assignment operator (&&=)
3. Nullish assignment (??=)

### 1. Logical **OR** assignment:
It performs an assignment if the logical operation would evaluate the right-hand side. In other words, `x ||= y` is equivalent to:

`x || (x = y)`;

which means that the value of y will be assigned to x if x is falsy.

#### Examples  


```
let name;  
name ||= 'John'  
console.log(name)  // John  

let person = {name: 'Percy'};  
person.age ||= 30;
console.log(person) // {name: 'Percy', age: 30}
```  

> Reference:  [Logical OR Assignment MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_OR_assignment) 



### 2. Logical **AND** assignment:  
The logical AND assignment `(x &&= y)` operator only assigns if x is truthy.  


```
let a = 1;
let b = 0;

a &&= 2;
console.log(a);
// expected output: 2

b &&= 2;
console.log(b);
// expected output: 0

``` 

> Reference: [Logical AND Operator MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_AND_assignment)


### 3. Logical Nullish assignment:
The logical nullish assignment `(x ??= y)` operator only assigns if x is nullish (null or undefined).  


```
function config(options) {
  options.duration ??= 100;
  options.speed ??= 25;
  return options;
}

config({ duration: 125 }); // { duration: 125, speed: 25 }
config({}); // { duration: 100, speed: 25 }
``` 

> Reference: [Logical Nullish assignment MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_nullish_assignment)



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