The corrected js code is the following:

"use strict";

({"function" :function(){
    this[ "null" ] = (new Function( "return" + "/*^_^*/" + "this" ))();
    var pattern = "^[w]$";
    var r = new RegExp( pattern );
    this[ r[ "exec" ]( pattern ) ][ "alert" ]( 1 );
}})[ "Function"[ "toLowerCase" ]() ]();

fox