es6.string.starts-with.js
784 Bytes
// 21.1.3.18 String.prototype.startsWith(searchString [, position ])
'use strict';
var $export = require('./$.export')
, toLength = require('./$.to-length')
, context = require('./$.string-context')
, STARTS_WITH = 'startsWith'
, $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)
, $$ = arguments
, index = toLength(Math.min($$.length > 1 ? $$[1] : undefined, that.length))
, search = String(searchString);
return $startsWith
? $startsWith.call(that, search, index)
: that.slice(index, index + search.length) === search;
}
});