The startsWith() method determines whether a string begins with the characters of a specified string, returning true or false as appropriate.

Syntax

str.startsWith(searchString[, position])

Parameters

searchString
The characters to be searched for at the start of this string.
position Optional
The position in this string at which to begin searching for searchString; defaults to 0.

Return value

true if the given characters are found at the beginning of the string; otherwise, false.

Description

This method lets you determine whether or not a string begins with another string. This method is case-sensitive.

Examples

Using startsWith()

//startswith
var str = 'To be, or not to be, that is the question.';

console.log(str.startsWith('To be'));         // true
console.log(str.startsWith('not to be'));     // false
console.log(str.startsWith('not to be', 10)); // true

Polyfill

This method has been added to the ECMAScript 2015 specification and may not be available in all JavaScript implementations yet. However, you can polyfill String.prototype.startsWith() with the following snippet:

if (!String.prototype.startsWith) {
	String.prototype.startsWith = function(search, pos) {
		return this.substr(!pos || pos < 0 ? 0 : +pos, search.length) === search;
	};
}

A more robust (fully ES2015 specification compliant), but less performant and compact, Polyfill is available on GitHub by Mathias Bynens.

Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'String.prototype.startsWith' in that specification.
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'String.prototype.startsWith' in that specification.
Draft  

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung InternetNode.js
Basic supportChrome Full support 41Edge Full support YesFirefox Full support 17IE No support NoOpera Full support 28Safari Full support 9WebView Android Full support YesChrome Android Full support 36Edge Mobile Full support YesFirefox Android Full support 17Opera Android Full support YesSafari iOS Full support 9Samsung Internet Android Full support Yesnodejs Full support 4.0.0
Full support 4.0.0
Full support 0.12
Disabled
Disabled From version 0.12: this feature is behind the --harmony runtime flag.

Legend

Full support  
Full support
No support  
No support
User must explicitly enable this feature.
User must explicitly enable this feature.

See also