--- /dev/null
+'use strict';
+
+var callable = require('../../../object/valid-callable')
+ , value = require('../../../object/valid-value')
+
+ , some = Array.prototype.some, apply = Function.prototype.apply;
+
+module.exports = function (predicate/*, thisArg*/) {
+ var k, self;
+ self = Object(value(this));
+ callable(predicate);
+
+ return some.call(self, function (value, index) {
+ if (apply.call(predicate, this, arguments)) {
+ k = index;
+ return true;
+ }
+ return false;
+ }, arguments[1]) ? k : -1;
+};