length

Summary

The length property represents the length of a string.

Description

This property returns the number of code units in the string. UTF-16, the string format used by JavaScript, uses a single 16-bit code unit to represent the most common characters, but needs to use two code units for less commonly-used characters, so it's possible for the value returned by length to not match the actual number of characters in the string.

For an empty string, length is 0.

The static property String.length returns the value 1.

Examples

var x = "Mozilla";
var empty = "";

console.log("Mozilla is " + x.length + " code units long");
/* "Mozilla is 7 code units long" */

console.log("The empty string is has a length of " + empty.length);
/* "The empty string is has a length of 0" */

Specifications

Specification Status Comment
ECMAScript 1st Edition. Standard Initial definition.
Implemented in JavaScript 1.0
ECMAScript 5.1 (ECMA-262)
The definition of 'String.prototype.length' in that specification.
Standard  
ECMAScript 6 (ECMA-262)
The definition of 'String.prototype.length' in that specification.
Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

Last updated by: Sevenspade,
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