I think I'm going mad!
I'm starting to write a little exercise for myself where I am going to have some divs that I can drag on the rightborder to increase or decrease the Div width. I also have a container Div that has a set width and I'm going to use this to determine a percentage - basically I'm going to be making some kind of bar-chart / histogram that you can edit.
I'm started writing my code and I thought I'd just make sure I could output the percentage.
Here's the perliminary code....
<style>
#container{width:500px;}
#dragDiv{border:1px solid #000;background-color:pink;width:100px;height:100px;}
</style>
</head>
<body>
<div id="container">
<div id="dragDiv"></div>
</div>
<script>
function dragOneSide(innDiv, outDiv){
if(document.getElementById(innDiv) && document.getElementById(outDiv)){
var iDiv = document.getElementById(innDiv),
oDiv = document.getElementById(outDiv);
// write out the width as a percentage
var iDivWidth = parseInt(iDiv.style.width),
oDivWidth = parseInt(oDiv.style.width);
//alert(document.getElementById("dragDiv").style.width);
iDiv.innerHTML = ((iDivWidth / oDivWidth) * 100);
}
}
window.onload = function(){
dragOneSide("dragDiv", "container");
}
</script>
Now the value in the iDiv was NaN? I found that rather odd. When trying to alert width I was getting a blank, literally an empty string! Rather odd I thought, especially as I wasn't trying to do anything complicated. I used firebug, set a breakpoint and observed the watch window. There was no value for the Div's width. I then put an inline style on the DIV like so...
<div id="container">
<div id="dragDiv" style="width:300px;">Hello World</div>
</div>
and low and behold I was now getting a value for the item! Now I don't like inline styles (who does) however I've never had this problem before and I've been using JavaScript and HTML for years - has anyone got an explaination for this? To retrieve the width not set by CSS do I have to use a different property like clientWidth
?
Ps. I haven't included any of the dragging code yet so please don't point that out.
The call to style.width retrieves the style value, which isn't set.
See this example. Yes, you want to use clientWidth in this case.
The simplest way is to use offsetWidth property:
var iDivWidth = parseInt(iDiv.style.offsetWidth),
oDivWidth = parseInt(oDiv.style.offsetWidth);
style.width is a DOM api which returns the width of an element when it's set inline or via the element.style.width = n + "px"; So that it reacts the way you describe it is as designed.
The offsetWidth like ioseb refers to is a DOM api call which returns the amount of horizontal space an element takes up.
Beware of the many inconsistencies between browsers .
PM5544...
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