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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.

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

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 Status Comment
ECMAScript Latest Draft (ECMA-262)
The definition of 'while statement' in that specification.
Living Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'while statement' in that specification.
Standard  
ECMAScript 5.1 (ECMA-262)
The definition of 'while statement' in that specification.
Standard  
ECMAScript 3rd Edition (ECMA-262)
The definition of 'while statement' in that specification.
Standard  
ECMAScript 1st Edition (ECMA-262)
The definition of 'while statement' in that specification.
Standard Initial definition

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes Yes Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support Yes Yes Yes Yes Yes Yes Yes

See also

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 Utoljára frissítve: fscholz,