JavaScript do/while statement

Definition and usage

The do/while statement creates a loop that executes the code block once before checking if the condition is true, and then it will repeat the loop as long as the condition is true.

When you want to run the loop at least once, use the do/while statement regardless of how it is.

JavaScript supports different types of loops:

  • for - Loop the code block multiple times
  • for/in - Loop through the properties of an object
  • for/of - Loop through the values of an iterable object
  • while - Loop the code block while the specified condition is true
  • do/while - Execute the code block once and then repeat the loop if the specified condition is true

Example

This loop will always execute at least once, even if the condition is false, because the code block is executed before the condition is tested:

var text = "";
var i = 0;
do {
  text += "The number is " + i;
  i++;
}
while (i < 5);

Try it yourself

Syntax

do {
  code block to be executed
}
while (condition);

Parameter value

Parameter Description
condition

Required. Define the condition that runs the loop (code block). If it returns true, the loop will restart, and if it returns false, the loop will end.

Note:If the condition is always true, the loop will never end. This may cause your browser to crash.

Note:If you use conditionally variable, please initialize it before the loop and increment it within the loop. If you forget to increase the variable, the loop will never end. This may also cause your browser to crash.

Technical details

JavaScript version: ECMAScript 1

Browser support

The numbers in the table specify the first browser version that fully supports this phrase.

Phrase Chrome IE Firefox Safari Opera
do/while Support 6.0 Support Support Support

Pages connexes

Tutoriel JavaScript :Boucle While JavaScript

Manuel de référence JavaScript :Instructions while JavaScript

Manuel de référence JavaScript :Instructions for JavaScript