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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(searchString, position){
      return this.substr(position || 0, searchString.length) === searchString;
  };
}

A more robust and optimized 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

FeatureChromeFirefoxEdgeInternet ExplorerOperaSafari
Basic Support4117(Yes)(No)289
FeatureAndroidChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic Support(Yes)36(Yes)17(No)(Yes)9

See also