How to run a javascript function during a mouseover on a div

Question

How can I get a Javascript function to run when the user mouses over a div tag?

Here is my div tag:

<div id="sub1 sub2 sub3">some text</div>

Answer 1

I'm assuming you want to display the welcome when you mouse over "some text".

As a message box, this will be:

<div id="sub1" onmouseover="javascript:alert('Welcome!');">some text</div>

As a tooltip, it should be:

<div id="sub1" title="Welcome!">some text</div>

As a new div, you can use:

<div id="sub1" onmouseover="javascript:var mydiv = document.createElement('div'); mydiv.height = 100; mydiv.width = 100; mydiv.zindex = 1000; mydiv.innerHTML = 'Welcome!'; mydiv.position = 'absolute'; mydiv.top = 0; mydiv.left = 0;">some text</div>

You should NEVER contain spaces in the id of an element.

Answer 2

This is badly formed HTML. You need to either have a single id or space separated classes. Either way if you're new I'd look into jQuery.

<div id="sub1">some text</div>

or

<div class="sub1 sub2 sub3">some text</div>

If you had the following HTML:

<div id="sub1">some text</div>
<div id="welcome" style="display:none;">Some welcome message</div>

jQuery

$(document).ready(function() {
    $('#sub1').hover(
      function() { $('#welcome').show(); },
      function() { $('#welcome').hide(); }
    );
});

Javascript

you'd probably want to include the events on your html:

<div id="sub1" onmouseover="showWelcome();" onmouseout="hideWelcome();">some text</div>

then your javascript would have these two functions

function showWelcome()
{
   var welcome = document.getElementById('welcome');
   welcome.style.display = 'block';
}

function hideWelcome()
{
   var welcome = document.getElementById('welcome');
   welcome.style.display = 'none';
}

Please note: this javascript doesn't take cross browser issues into consideration. for this you'd need to elaborate on your code, just another reason to use jquery.