blob: e4fe655c7e912f9cb1e345e17861eb4058c88897 [file] [log] [blame]
'use strict';
var $ = require('../internals/export');
var getOwnPropertyDescriptor = require('../internals/object-get-own-property-descriptor').f;
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 IS_PURE = require('../internals/is-pure');
var nativeStartsWith = ''.startsWith;
var min = Math.min;
var CORRECT_IS_REGEXP_LOGIC = correctIsRegExpLogic('startsWith');
// https://github.com/zloirock/core-js/pull/702
var MDN_POLYFILL_BUG = !IS_PURE && !CORRECT_IS_REGEXP_LOGIC && !!function () {
var descriptor = getOwnPropertyDescriptor(String.prototype, 'startsWith');
return descriptor && !descriptor.writable;
}();
// `String.prototype.startsWith` method
// https://tc39.github.io/ecma262/#sec-string.prototype.startswith
$({ target: 'String', proto: true, forced: !MDN_POLYFILL_BUG && !CORRECT_IS_REGEXP_LOGIC }, {
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;
}
});