I have a script that dynamically inserts a div containing text in the dom. The text content is not known in advance.
I need to know the width of this div, but it seems that that the return value of document.defaultView.getComputedStyle(node, "").getPropertyValue("width") or node.offsetWidth cannot be trusted.
I used setInterval to log it, and the value changes over time. For instance, in my case it starts with 929px and then changes to 908px.
This div is in position absolute, it has whitespace nowrap, so I don't think it is being "pushed" by other dom elements or that it somehow changes once inserted.
Is there an elegant way to retrieve the width, or do I have to use an ugly setTimeout to retrieve it once the return value is stable ?
Try:
yourDOMElement.getClientBoundingRect()
This will return an object with top, left, right, bottom, height and width attributes. This should be cross-browser.
Note: If you are going to work with the position attributes (top, left, right, bottom, height) of the returned, take into account scroll offset if necessary.
Update: To ensure this works on older browsers that don't have the width/height attribute, calculate it subtracting right/bottom from left/top.
The viewport can change its size because of the scrollbar. Once the scrollbar appears, its width can no longer be used by the document. Force the scrollbar to exist before you measure the size by adding overflow: scroll or overflow-y:scroll to the <html> element.
The size of a block-level element is, by default, its container width minus margins and padding (even if it's positioned absolutely), which is ultimately the wiewport width unless you set a fixed width somewhere along the way.
Using jQuery, you should be able to do this:
var width = $("div-selector").width();
this is fairly easy?
open the page in a browser and press f12. With firefox there is a button "inspect element" on top and in chrome it's on the bottom. Click it and hover your mouse over it. This should give you the height and width in px. Never been wrong for me.
if it still doesn't show, click it and you can see it in the css panel of the console.
Related
I want to obtain the dimensions of a DIV element (used to display a popup menu at the cursor position) while it's style.display='none;', however the dimensions of the DIV always return 0. The only way I seem to be able to get the dimensions is to make the DIV style.display='block;' at 0,0 and then move it to the required position, but that looks jumpy.
I've tried making the DIV visible outside of the visible screen area but that doesn't work. Is there a way to get the clientWidth and clientHeight values whilst the DIV is hidden?
If your DIV is not visible, you won't be able to get its dimensions.
However, there is a workaround. Your div has to be "visible", but that doesn't mean it's opacity and position have to be 1 and relative.
Set the opacity to 0 and the position to "absolute" and you'll be able to get the DIV dimensions.
EDIT
Since I think more people will have a similar problem, I feel I should explain my answer a little more.
If you try to get the size of a hidden element with JavaScript, you will always get 0.
So there are techniques to get the real size without displaying the element to the user. My favourite is the one I already wrote about above. Here are the more detailed steps:
you set the elements opacity to 0. This way it won't be displayed to the end user while you are getting the dimensions.
you set the element position to "absolute". This way it won't take up any space.
now it's safe to set the display to "inline-block".
you read the elements dimensions. This time you'll get the real values.
You set the display back to "hidden" and set the opacity and position back to its original values.
And now you have the size of a hidden element.
If you'd like to know the size of an element onscreen without it being visible you need it to be painted to the screen but not shown.
In order to get clientHeight and clientWidth you need it to be rendered so the calculations can be performed based on the screens current state (unless you have pre-programmed width and height, which I'm guessing you don't)
you can find out more information at MDN here
So you have options:
create your div offscreen using positioning (fixed or absolute) combined with z-index or opacity
use width: 0 and height: 0 and overflow: hidden then use scrollHeight and scrollWidth to find the overflow size
choose which option is best for your site, considering things like responsiveness and screen reflows and repaints
I am using the following jQuery to work out the width of a div (thats in %), to then tell another div to set it's height to that in pixels.
<script>
$("#top").height($("#left").width());
$("#bottom").height($("#left").width());
</script>
It's working really well. Now my next problem is, that I want my div called 'wrapper' to have a padding-top or margin-top of the pixel value it returns for the height. I tried changing 'height' to 'padding-top', but that didn't seem to work.
The end result is a web page with a series of 4 black div acting as a border around the edge, it calculates 5% of the with of the window, and that determine's the pixel value for how how the top and bottom black div's are. That way it's exactly even. Now I want my inside wrapper div, to start exactly that far down the web page too.
Use the jQuery outerWidth function to retrieve the width inclusive of padding, borders and optionally margin as well (if you send true as the only argument to the outerWidth method).
Tested Solution: Find height of a div and use it as margin top of another div.
$('.topmargindiv').css('margin-top', function() {
return $('.divheight').height();
});
I'm trying to get the height of an initially hidden div element in Netscape and Firefox using javascript (it works fine in IE). I have tried using MyElement.scrollHeight, MyElement.offetHeight, MyElement.style.height and many different ways of setting the element initially visible, getting the height and then hiding it again. I keep getting a value of 0. Any thoughts?
Correct me if I'm wrong (Which I may be), but from doing some research, elements with display: none have no height.
To get the height, you would need to unhide them, get the height, then rehide them. Issues like this have popped up in the past like so:
jQuery: height()/width() and "display:none"
jQuery: Get height of hidden element in jQuery
(Both jQuery examples, but you get the point)
Hidden elements in Netscape is not accessible.
you can set that position with styling hole of div out of your screen. for example move it to -9999 on top left. then you can access that's attributes like height and width.
you can also visible that element and get your attribute and hide it again, but it is not usual because your element will be show a little bit of the second and user maybe feel jumping on screen.
you should position it by setting style to "absolute" and "top" to -9999px or more (depend of your project height) and then get your element height and width with DOM and anythings that you want ...
This is a followup to my question here. I would like to understand why applying position:absolute to the CSS of a div via jQuery fails, while applying it in a static style works. Here are two jsfiddle examples:
Works: http://jsfiddle.net/jasper/Ty6Af/2/
No worky: http://jsfiddle.net/Ty6Af/3/
Note that the only difference between the two is where I apply position:absolute. Vertical centering always works, but horizontal centering does not work when the page loads for the first time. If you manually re-size the window the div will center correctly.
All of my testing has been on Chrome under Ubuntu thus far.
Anyway, I'm just now delving into the world of web development and these are exactly the kinds of 'quirks' that I need to begin understanding.
EDIT:
#Jasper found something interesting. If you make two calls to .css(), first applying position and subsequently applying a margin, it works. I would love to understand why. Here is an example: http://jsfiddle.net/jasper/Ty6Af/5/
So the issue is with how the width of the div is calculated by the browser depending on its position.
If the div is set to position : static (by default) then it's width is 100% of it's parents width and the element is not allowed to move around the page.
If the div is set to position : relative then it's width is 100% of it's parents width but it can be moved around with left.
If the div is set to position : absolute then its width is determined by the actual content of the div, for instance if there is only a 200px wide <span> element within the div then the div will be 200px wide.
You can test these observations by changing the CSS of your jsfiddle to specify position : relative (etc...) and remove the JavaScript that makes the div position : absolute, then use your Developer Tools to inspect the element and it's calculated width.
The problem with your code is that it sets the position : absolute at the same time it sets the margin of the element by using its width/height (which are calculated differently depending on the position of the element).
If you want to set the position of the div in JavaScript then you can do something like this:
$(function() {
//notice I cached the selector so it can be used in the future as well as set the position of the div
$signuparea = $('#signuparea').css({position : 'absolute'});
$(window).resize(function() {
$signuparea.css({
'margin-top' : '-' + Math.round($signuparea.height() / 2) + 'px',
'margin-left' : '-' + Math.round($signuparea.width() / 2) + 'px',
});
}).trigger('resize');
});
Here's a jsfiddle: http://jsfiddle.net/jasper/Ty6Af/8/
I believe the problem is that when you apply your left and right in your second fiddle, you have yet to add position absolute to the div. Hence, the browser has no idea what do with the left and right values and ignores them initially.
Practically speaking in your second fiddle, you only actually add the position:absolute on the resize trigger. So before you resize your actual div has no positioning.
If you instead add the position absolute on load it works fine:http://jsfiddle.net/Ty6Af/9/
Notice that if you give it position:relative from the start (like this http://jsfiddle.net/Ty6Af/11/ ) it allready applies both the left and right value. The reason you can't actually see the effect of "left" is because it is a block element.
I hope that answers your question, I'm not quite clear on where you are stuck.
http://jsfiddle.net/Ty6Af/7/ this should work, the trigger function in jquery has bugs with chrome so you have to run the function on load too.
The problem seems to be that position:absolute; negates the current layout and requires you to position it.....
See: http://jsfiddle.net/ZHaRD/
Which Jasper explains much more eloquently than myself!
I have a <h3> tag with limited height (100 px for example, position: absolute) and the text overflows it.
What I would like to do is slide it down over to the height that is needed when the mouse is over it and back to original height (100px).
I hope you understood what I mean
I don't think it uses slidedown() function for that and I am very weak in animate function. Any help please?
You can nest a div inside the h3 that contains the content and then use the h3 as a masking container (use overflow:hidden). When the user mouses over, fire a function that get's the height of the interior div (make sure to include any margins or padding). Then execute you height adjust animate function (In jquery, something like $('h3').animate({height: heightVar}); )The mouseout fires a function that restores the height of the h3 back to 100px.
Here's a sample: http://jsfiddle.net/XR9fb/
You can get the real height of the element with the scrollHeight property. Now, I don't really know much of jQuery, but I imagine you could just call animate to set the height CSS property to the scrollHeight of the element when the mouse hovers it, and return to the original height when the mouse moves out of it.
If the height of the element isn't fixed, you can salve the current height somewhere before displaying the full element, and when the mouse leaves the element you just restores this state.