--- /dev/null
+'use strict';
+
+var toInteger = require('../../../number/to-integer')
+ , value = require('../../../object/valid-value')
+
+ , min = Math.min, max = Math.max;
+
+module.exports = function (searchString/*, endPosition*/) {
+ var self, start, endPos;
+ self = String(value(this));
+ searchString = String(searchString);
+ endPos = arguments[1];
+ start = ((endPos == null) ? self.length :
+ min(max(toInteger(endPos), 0), self.length)) - searchString.length;
+ return (start < 0) ? false : (self.indexOf(searchString, start) === start);
+};