Question

var flashStep = 1;
function flash() {
 if(flashStep==1) {
 document.bgColor="FFFF00";
 flashStep=2;
 }
 else {
 document.bgColor="FF0000";
 flashStep=1;
 }
}
var task = window.setInterval("flash()",1000);

This code is supposed to make the screen flash, but does not work at all. http://jsfiddle.net/phjnM/2/. Why does this not work, it looks flawless to me

Answer 1

The problem is the (global) scope being applied when you pass a string to setInterval. If you pass a function reference instead it works:

var task = window.setInterval(flash,1000);

See http://jsfiddle.net/phjnM/7/

The other option is in jsfiddle choose the “nowrap” option so that your code isn’t defined in an onload/onready handler’s scope…