[jaroslav.tavgen]

"use strict"
a = "b"

Но не в этом случае:

<div id="id1" onclick="Function1()">Click on me</div>
<script>
"use strict"
var id1 = document.getElementById("id1");
id1.outerHTML = id1.outerHTML.replace('onclick="Function1()"', 'onclick="Function2()"');

alert(id1.outerHTML);

function Function1(){

    alert('Function1 is executed!');

}

function Function2(){

    alert('Function2 is executed!');

}


</script>