Web/JavaScript/Reference/statements/while

The while statement creates a loop that executes a specified statement as long as the test condition evaluates to true. The condition is evaluated before executing the statement.

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Syntax

while (condition)
  statement

condition: An expression evaluated before each pass through the loop. If this condition evaluates to true, statement is executed. When condition evaluates to false, execution continues with the statement after the while loop.
statement: An optional statement that is executed as long as the condition evaluates to true. To execute multiple statements within the loop, use a block statement ({ ... }) to group those statements. Note: Use the break statement to stop a loop before condition evaluates to true.

Examples

Using while

The following while loop iterates as long as n is less than three.

var n = 0;
var x = 0;

while (n < 3) {
  n++;
  x += n;
}

Each iteration, the loop increments n and adds it to x. Therefore, x and n take on the following values:

After the first pass: n = 1 and x = 1
After the second pass: n = 2 and x = 3
After the third pass: n = 3 and x = 6

After completing the third pass, the condition n < 3 is no longer true, so the loop terminates.

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'while statement' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`while`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 3	Opera Full support 3	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100

Legend

Full support: Full support