JavaScript Comma Operator

Comma Operator (,) mainly evaluates its operands from left to right sequentially and returns the value of the rightmost operand. A comma operator is used as a separator for multiple expressions at a place that requires a single expression. When a comma operator is placed in an expression, it executes each expression and returns the rightmost expression.

Syntax:

Expression1, Expression2, Expression3, ...so on

In the above syntax, multiple expressions are separated using a comma operator. During execution, each expression will be executed from left to right and the rightmost expression will be returned.

Example 1: Below is an example of the Comma operator.

javascript

function Func1() {
    console.log('one');
    return 'one';
}
function Func2() {
    console.log('two');
    return 'two';
}
function Func3() {
    console.log('three');
    return 'three';
}

// Three expressions are
// given at one place
let x = (Func1(), Func2(), Func3());

console.log(x);

Output

one
two
three
three

Example 2: The most useful application of the comma operator is in loops. In loops, it is used to update multiple variables in the same expression.

javascript

for (let a = 0, b =5; a <= 5; a++, b--) {
    console.log(a, b);
}

Output

0 5
1 4
2 3
3 2
4 1
5 0

We have a complete list of JavaScript Operators, to check those please go through the Javascript Operators Complete Reference article. 

Supported Browsers:

• Google Chrome
• Internet Explorer
• Firefox
• Apple Safari
• Opera