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JavaScript Assignment Operators

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Assignment Operators

Assignment operators are used to assign values to variables in JavaScript.

Syntax:

data=value

Example:

// Lets take some variables
x=10
y=20

x=y // Here, x is equal to 20
y=x // Here, y is equal to 10

Assignment Operators List

There are so many assignment operators as shown in the table with the description.

OPERATOR NAMESHORTHAND OPERATORMEANING
Addition Assignmenta+=ba=a+b
Subtraction Assignmenta-=ba=a-b
Multiplication Assignmenta*=ba=a*b
Division Assignmenta/=ba=a/b
Remainder Assignmenta%=ba=a%b
Exponentiation Assignmenta**=ba=a**b
Left Shift Assignmenta<<=ba=a<<b
Right Shift Assignmenta>>=ba=a>>b
Bitwise AND Assignmenta&=ba=a&b
Bitwise OR Assignmenta|=ba=a | b
Bitwise XOR Assignmenta^=ba=a^b

Logical AND Assignment

a&&=b

x && (x = y)

Logical OR Assignment

||=

x || (x = y)

Nullish coalescing Assignment

??=

x ?? (x = y)

Below we have described each operator with an example code:

Addition Assignment Operator(+=)

The Addition assignment operator adds the value to the right operand to a variable and assigns the result to the variable. Addition or concatenation is possible. In case of concatenation then we use the string as an operand.

Example:

Javascript
let a = 2;
const b = 3;

// Expected output: 2
console.log(a);

// Expected output: 4
console.log(a = b + 1);

Output:

2
4

Subtraction Assignment Operator(-=)

The Substraction Assignment Operator subtracts the value of the right operand from a variable and assigns the result to the variable.

Example:

Javascript
let yoo = 4;

// Expected output 3
console.log(foo = yoo - 1); 

Output:

3

Multiplication Assignment Operator(*=)

The Multiplication Assignment operator multiplies a variable by the value of the right operand and assigns the result to the variable.

Example:

Javascript
let yoo = 4;

// Expected output 3
console.log(foo = yoo - 1); 

Output:

10

Division Assignment Operator(/=)

The Division Assignment operator divides a variable by the value of the right operand and assigns the result to the variable.

Example:

Javascript
let yoo = 10;
const moo = 2;

// Expected output 5
console.log(yoo = yoo / moo);

// Expected output Infinity    
console.log(yoo /= 0);

Output:

5
Infinity

Remainder Assignment Operator(%=)

The Remainder Assignment Operator divides a variable by the value of the right operand and assigns the remainder to the variable.

Example:

Javascript
let yoo = 50;

// Expected output 0
console.log(yoo %= 10);

Output:

0

Exponentiation Assignment Operator

The Exponentiation Assignment Operator raises the value of a variable to the power of the right operand.

Example:

Javascript
let yoo = 50;

// Expected output 0
console.log(yoo %= 10);

Output:

4

Left Shift Assignment Operator(<<=)

This Left Shift Assignment Operator moves the specified amount of bits to the left and assigns the result to the variable.

Example:

Javascript
let yoo = 5;

// Expected output 20(In Binary 10100)
console.log(yoo <<= 2);

Output:

20

Right Shift Assignment Operator(>>=)

The Right Shift Assignment Operator moves the specified amount of bits to the right and assigns the result to the variable.

Example:

Javascript
let yoo = 5;

// Expected Output 1(In binary 001)
console.log(yoo >>= 2); 

Output:

1

Bitwise AND Assignment Operator(&=)

The Bitwise AND Assignment Operator uses the binary representation of both operands, does a bitwise AND operation on them, and assigns the result to the variable.

Example:

Javascript
let yoo = 5;

// Expected output 0(In binary 000)
console.log(yoo &= 2);

Output:

0

Btwise OR Assignment Operator(|=)

The Btwise OR Assignment Operator uses the binary representation of both operands, does a bitwise OR operation on them, and assigns the result to the variable.

Example:

Javascript
let yoo=5;
    
// Expected output 7(In binary 111)
console.log(yoo|=2);

Output:

7

Bitwise XOR Assignment Operator(^=)

The Bitwise XOR Assignment Operator uses the binary representation of both operands, does a bitwise XOR operation on them, and assigns the result to the variable.

Example:

Javascript
let yoo = 5;

// Expected output 7(In binary 111)
console.log(yoo ^= 2);

Output:

7

Logical AND Assignment Operator(&&=)

The Logical AND Assignment assigns the value of into only if is a truthy value.

Example:

Javascript
let name = {
    firstName: "Ram",
    lastName: "",
};

console.log(name.firstName);

// Changing the value using logical 
// AND assignment operator 
name.firstName &&= "Shyam";

// Here the value changed because 
// name.firstName is truthy 
console.log(name.firstName);

console.log(name.lastName);

// Changing the value using logical 
// AND assignment operator 
name.lastName &&= "Kumar";

// Here the value remains unchanged 
// because name.lastName is falsy 
console.log(name.lastName); 

Output
Ram
Shyam



Logical OR Assignment Operator(||=)

The Logical OR Assignment Operator is used to assign the value of y to x if the value of x is falsy.

Example:

Javascript
let name = {
    firstName: "Ram",
    lastName: "",
};

console.log(name.firstName);

// Changing the value using logical 
// OR assignment operator 
name.firstName ||= "Shyam";

// But value does not change because 
// name.firstName is truthy 
console.log(name.firstName);

console.log(name.lastName);

// Changing the value using logical 
// OR assignment operator 
name.lastName ||= "Kumar";

// The value changes because name.lastName is falsy 
console.log(name.lastName); 

Output
Ram
Ram

Kumar

Nullish coalescing Assignment Operator(??=)

The Nullish coalescing Assignment Operator assigns the value of y to x if the value of x is null.

Example:

Javascript
let x = 12;
let y = null;

let z = 13;

// The value of x will become 
// unchanged because x is not nullish. 
x ??= z;

// The value of y will be 
// changed because y is nullish. 
y ??= z;

console.log(x) // 12 
console.log(y) // 13

Output
12
13


Supported Browsers: The browsers supported by all JavaScript Assignment operators are listed below:




Last Updated : 12 Mar, 2024
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