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JavaScript event window.onload not triggered
Asked Answered
Solved javascriptonloadonload-event
S

12

72

I've got the following code in a website:

 window.onload = resize;
 window.onresize = resize;

 function resize(){
  heightWithoutHeader = (window.innerHeight - 85) + "px"; 
  document.getElementById("main-table").style.height = heightWithoutHeader;
  document.getElementById("navigation").style.height = heightWithoutHeader;
 }

The onresize works fine, but the onload event never fires. I've tried it in Firefox and Chrome and neither of them works.

Thank you for your help and go for the reputation! ;D

Sexdecillion answered 11/5, 2010 at 12:56 Comment(3)
When are you running this code? Is it possible that the onload is being being overridden later, or is being attached after the load event fires? – Apul
You were right. window.onload was obviously overwritten by <body onload=...> later. Post your comment as an answer please, so I can tick it as the right one. – Sexdecillion
Done :) Glad you resolved it! – Apul
A
127

I think what's probably happening here is that your window.onload is being overridden later, check to make sure that it's not via things like <body onload="">

You can check this by alert(window.onload) in your re-size function, to see what's actually attached there.

Apul answered 11/5, 2010 at 14:31 Comment(3)
I was unaware that window.onload would get overwritten if you had it in multiple .js files, which makes sense, but nice to know! – Croesus
A little note for who has similar issue. In my case, I've used dynamic HTML, populating inside document via win = window.open("about:blank","",""); win.document.write(htmlcontent); . But my javascript form commit action was never triggered, due to the onload event was not called. I've added win.onload(null); via this answer, and it worked. – Wharve
Important to say that the window.onload event can be cut and paste down the script after the body onload code fires. Then the window.onload script will work as well. – Wegner
F
48

I had this happen when I added 3rd party jQuery code we needed for a partner. I could have easily converted my antiquated window.onload to a jQuery document ready. That said, I wanted to know if there is a modern day, cross browser compatible solution.

There IS!

window.addEventListener ? 
window.addEventListener("load",yourFunction,false) : 
window.attachEvent && window.attachEvent("onload",yourFunction);

Now that I know ... I can convert my code to use the jQuery route. And, I will ask our partner to refactor their code so they stop affecting sites.

Source where I found the fix --> http://ckon.wordpress.com/2008/07/25/stop-using-windowonload-in-javascript/

Fawcett answered 15/7, 2013 at 18:33 Comment(3)
I don't understand why but this code is not working for me. I replaced yourFunction with my function runCode I even moved the addEventListener line to the bottom of my script as suggested below. – Transatlantic
I know the ternary operator but I don't understand what window.addEventListener ? does, does it check if an event listener already exists on window? – Transatlantic
This worked for me. Thank god. Note that you need to have a function to call ;-) I placed it in the <head> – Elanaeland
I
9

This answer is for those who came here because their window.onload does not trigger.

I have found that for the following to work

window.onload = myInitFunction;

or

window.addEventListener("load", myInitFunction);

the referred function (myInitFunction in this case) must reside (or be defined) within the same <script>-element or in a <script>-element that occurs before the <script>-element where the onload event is established. Otherwise it will not work.

So, this will not work:

<html>
  <head>
    <title>onload test</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    <script>
      window.addEventListener("load", myInitFunction)
    </script>

    <script>
      function myInitFunction() {
        alert('myInitFunction');
      }
    </script>

  </head>
  <body>
    onload test
  </body>
</html>

But this will work:

<html>
  <head>
    <title>onload test</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    <script>
      function myInitFunction() {
        alert('myInitFunction');
      }
    </script>

    <script>
      window.addEventListener("load", myInitFunction)
    </script>

  </head>
  <body>
    onload test
  </body>
</html>

And this will work (since we only have one <script>-element):

<html>
  <head>
    <title>onload test</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    <script>
      window.addEventListener("load", myInitFunction)

      function myInitFunction() {
        alert('myInitFunction');
      }
    </script>

  </head>
  <body>
    onload test
  </body>
</html>

If you for some reason have two <script>-elements and cannot (or do not want to) merge them and you want the onload to be defined high up (i.e. in the first element), then you can solve it by

instead of writing

window.onload = myInitFunction;

you write

window.onload = function() { myInitFunction() };

or, instead of writing

window.addEventListener("load", myInitFunction);

you write

window.addEventListener("load", function() { myInitFunction() });

Another way to solve it is to use the old

<body onload="myInitFunction()">
Interloper answered 16/8, 2020 at 13:34 Comment(0)
P
6

Move the window.onload line to the end of the javascript file or after the initial function and it will work:

function resize(){
    heightWithoutHeader = (window.innerHeight - 85) + "px"; 
    document.getElementById("main-table").style.height = heightWithoutHeader;
    document.getElementById("navigation").style.height = heightWithoutHeader;
}
// ...
// at the end of the file...
window.onload = resize;
window.onresize = resize;

But it's a best practice if you don't replace the onload too. Instead attach your function to the onload event:

function resize(){
    heightWithoutHeader = (window.innerHeight - 85) + "px"; 
    document.getElementById("main-table").style.height = heightWithoutHeader;
    document.getElementById("navigation").style.height = heightWithoutHeader;
}
// ...
// at the end of the file...
window.addEventListener ? 
    window.addEventListener("load",resize,false) 
    : 
    window.attachEvent && window.attachEvent("onload",resize);

That worked for me and sorry for my english.

Paymaster answered 30/12, 2016 at 4:32 Comment(1)
Thanks you save my day its working for me too. – Jennyjeno
M
3

For me, window.onload was not working when wrote inside script type="text/javascript tag.

Instead, needed to write the same in script language="Javascript" type="text/javascript tag and it worked fine.

Muff answered 1/7, 2017 at 9:55 Comment(0)
S
2

In my case

window.addEventListener("load", function() {
    myDropdownFunction();
});

surprisingly (for me) didn't help (I tried to set a value for dropdown when user uses browser backwards button). And window.onload didn't work for the reason Nick Craver♦ explained here above - it was overridden by <body onload="...">.

So I tried this using jQuery and it worked like a charm:

$(window).on('pageshow', function() {
    alert("I'm happy");
});
Straka answered 7/4, 2021 at 20:7 Comment(0)
A
1

This works for me, i think your problem is somewhere else:

 function resize(){
  var tester = document.getElementById("tester"),
      html = tester.innerHTML

  tester.innerHTML = html + "resize <br />"
 }  

window.onload = resize;
window.onresize = resize;

you can test it yourself here: http://jsfiddle.net/Dzpeg/2/

are you sure its the only event called onLoad ? Maybe an other onLoad event creates a conflict

Abscise answered 11/5, 2010 at 13:17 Comment(0)
S
0

put "_blank" as the target param has solved in my case

let wind    = open(url,"_blank","options here")
wind.onload = .... // works fine now
Supinate answered 25/10, 2021 at 21:51 Comment(0)
D
0

Just in case someone finds it useful, I was calling twice the function, instead of once:

window.onload = function() {...}
Derman answered 24/8, 2022 at 16:3 Comment(0)
S
0

In my case the problem was that my script was being loaded dynamically by another one (e.g.: with $.getScript()) and when it ran the window 'load' event had already fired.

My solution:

  if (
    document.readyState === "complete" ||
    document.readyState === "interactive"
  ) {
    // load event already fired, this may happen if this script is loaded dynamically.
    // Run immediately.
    execOnLoad();
  } else {
    // SEE: https://mcmap.net/q/273263/-javascript-event-window-onload-not-triggered
    window.addEventListener
      ? window.addEventListener("load", execOnLoad, false)
      : window.attachEvent && window.attachEvent("onload", execOnLoad);
  }
Sapphera answered 14/10, 2022 at 10:55 Comment(0)
C
-1

This will be work when you call the "window.onload" next to the function resize()

Claiborne answered 11/5, 2010 at 13:6 Comment(0)
B
-4

If it's really in that order, it's definitely not going to work. You can't assign a function to an event handler before the function itself is declared.

Blasting answered 11/5, 2010 at 12:58 Comment(2)
As Nick Craver said, it would be helpful to know the larger context of this and when it's actually being called. – Blasting
wrong answer: in the same javascript scope it is allowed, but not recommended, to declare a variable or function after its use. try : "var a = fun(42); function fun(n) { return n; }; console.log(a);" – Isaiah

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