19 lines
762 B
JavaScript
19 lines
762 B
JavaScript
|
// 21.1.3.18 String.prototype.startsWith(searchString [, position ])
|
||
|
|
'use strict';
|
||
|
|
var $export = require('./_export');
|
||
|
|
var toLength = require('./_to-length');
|
||
|
|
var context = require('./_string-context');
|
||
|
|
var STARTS_WITH = 'startsWith';
|
||
|
|
var $startsWith = ''[STARTS_WITH];
|
||
|
|
|
||
|
|
$export($export.P + $export.F * require('./_fails-is-regexp')(STARTS_WITH), 'String', {
|
||
|
|
startsWith: function startsWith(searchString /* , position = 0 */) {
|
||
|
|
var that = context(this, searchString, STARTS_WITH);
|
||
|
|
var index = toLength(Math.min(arguments.length > 1 ? arguments[1] : undefined, that.length));
|
||
|
|
var search = String(searchString);
|
||
|
|
return $startsWith
|
||
|
|
? $startsWith.call(that, search, index)
|
||
|
|
: that.slice(index, index + search.length) === search;
|
||
|
|
}
|
||
|
|
});
|