diff --git a/src/replacements/string/_String_startsWith.js b/src/replacements/string/_String_startsWith.js
new file mode 100644
index 00000000..db6ef0f1
--- /dev/null
+++ b/src/replacements/string/_String_startsWith.js
@@ -0,0 +1,12 @@
+var _String_startsWith = F2(
+    function (prefix, str) {
+        var prefixLength = prefix.length;
+        var i = -1;
+        if (str.length < prefixLength) {
+            return false;
+        }
+        while (++i < prefixLength) {
+            if (prefix[i] !== str[i]) { return false; }
+        }
+        return true;
+    });
\ No newline at end of file