Correct usage of addEventListener() / attachEvent()?

Question

Hi guys! I'm wondering how to use "addEventListener" resp. "attachEvent" correctly!?

window.onload=function(myFunc1){ // do something }

function myFunc2(){ // do something }
if (window.addEventListener){ window.addEventListener('load', myFunc2, false); } 
else if (window.attachEvent){ window.attachEvent('onload', myFunc2); }

...

or

function myFunc1(){ // do something }
if (window.addEventListener){ window.addEventListener('load', myFunc1, false); } 
else if (window.attachEvent){ window.attachEvent('onload', myFunc1); }

function myFunc2(){ // do something }
if (window.addEventListener){ window.addEventListener('load', myFunc2, false); } 
else if (window.attachEvent){ window.attachEvent('onload', myFunc2); }

...

?

Is this cross-browser secure or should I better go with sth. like this:

function myFunc1(){ // do something }
function myFunc2(){ // do something }
...

function addOnloadEvent(fnc){
  if ( typeof window.addEventListener != "undefined" )
    window.addEventListener( "load", fnc, false );
  else if ( typeof window.attachEvent != "undefined" ) {
    window.attachEvent( "onload", fnc );
  }
  else {
    if ( window.onload != null ) {
      var oldOnload = window.onload;
      window.onload = function ( e ) {
        oldOnload( e );
        window[fnc]();
      };
    }
    else
      window.onload = fnc;
  }
}

addOnloadEvent(myFunc1);
addOnloadEvent(myFunc2);
...

AND: Say "myfunc2" is for IE 7 only. How to modify the correct/preferred method accordingly?

Thank you so much!

Answer 1

As for your question: your first method seems weird. The second and the third are both probably OK.

However a more general remark is probably appropriate: the only reasonable cross-browser secure way of doing this stuff (as well as more-or-less any JS stuff in the browser) is by using a javascript framework such as jQuery, Dojo, MochiKit, and the like. So, unless you are developing a framework of your own, DO NOT try to do whatever you are trying to do now.

Many people spent uncountable sleepless nights fighting these issues so that you could now code JS comfortably.

AND: There are zillions of ways of detecting the browser and those again depend on what you need. If you really only need to detect IE7 (who'd want that??), you might try simply checking navigator.appVersion.indexOf("MSIE 7.")