Why it doesn't work?

Question

https://code.sololearn.com/Wpfm1fw1DSrH/?ref=app

Answer 1

Some other instances of script executing before DOM loads:

https://www.sololearn.com/Discuss/1190390/?ref=app
https://www.sololearn.com/Discuss/735043/?ref=app

Answer 2

https://www.sololearn.com/post/7444/?ref=app

Answer 3

Try

onload = function() {

for (i=1;i<=256;i++) {
var d = document.createElement("div");
document.body.appendChild(d);
var t = document.createTextNode("pizza");
d.appendChild(t);
}

}