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    String.prototype.startsWith()

    This is an experimental technology, part of the ECMAScript 6 (Harmony) proposal.
    Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future version of browsers as the spec changes.

    The startsWith() method determines whether a string begins with the characters of another 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.

    Description

    This method lets you determine whether or not a string begins with another string.

    Examples

    Using 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 6 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) {
        position = position || 0;
        return this.lastIndexOf(searchString, position) === position;
      };
    }
    

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 41 17 (17) Not supported Not supported Not supported
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support Not supported 36 17.0 (17) Not supported Not supported Not supported

    See also

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