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


str.startsWith(searchString[, position])


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.


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


Using startsWith()

let 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


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) {
    Object.defineProperty(String.prototype, 'startsWith', {
        value: function(search, rawPos) {
            var pos = rawPos > 0 ? rawPos|0 : 0;
            return this.substring(pos, pos + search.length) === search;

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


ECMAScript (ECMA-262)
The definition of 'String.prototype.startsWith' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
startsWithChrome Full support 41Edge Full support 12Firefox Full support 17IE No support NoOpera Full support 28Safari Full support 9WebView Android Full support ≤37Chrome Android Full support 36Firefox Android Full support 17Opera Android Full support 24Safari iOS Full support 9Samsung Internet Android Full support 3.0nodejs Full support 4.0.0
Full support 4.0.0
Full support 0.12
Disabled From version 0.12: this feature is behind the --harmony runtime flag.


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

See also