debian-mirror-gitlab/core-js/modules/es.string.starts-with.js
2019-09-25 13:30:05 +05:30

23 lines
999 B
JavaScript

'use strict';
var $ = require('../internals/export');
var toLength = require('../internals/to-length');
var notARegExp = require('../internals/not-a-regexp');
var requireObjectCoercible = require('../internals/require-object-coercible');
var correctIsRegExpLogic = require('../internals/correct-is-regexp-logic');
var nativeStartsWith = ''.startsWith;
var min = Math.min;
// `String.prototype.startsWith` method
// https://tc39.github.io/ecma262/#sec-string.prototype.startswith
$({ target: 'String', proto: true, forced: !correctIsRegExpLogic('startsWith') }, {
startsWith: function startsWith(searchString /* , position = 0 */) {
var that = String(requireObjectCoercible(this));
notARegExp(searchString);
var index = toLength(min(arguments.length > 1 ? arguments[1] : undefined, that.length));
var search = String(searchString);
return nativeStartsWith
? nativeStartsWith.call(that, search, index)
: that.slice(index, index + search.length) === search;
}
});