I got this style applied to a div
div#content {
border: 1px solid skyblue;
}
and i want to be able to alert the width of the border, I have tried with this:
window.alert( document.getElementById( "content" ).style.borderWidth );
I heard that depends of the browser maybe you can help me
I'm using Firefox 18
Please try the below javascript:
alert($("#content").css("border-left-width")); //using jquery.
or
alert(getComputedStyle(document.getElementById('content'),null).getPropertyValue('border-left-width'));//without jquery.
getComputedStyle(element, pseudo)
element:The element to get a styling for
pseudo:A pseudo-selector like ‘hover’ or null if not needed.
Reference link: http://javascript.info/tutorial/styles-and-classes-getcomputedstyle
I might be too late but as you never marked it as answered, I thought I could give it a try.
If your problem was compatibility between browser I would create a custom method that I could use in almost every browser there is (that means going back to the very basics).
I actually dug a lot to do this. I use some of the code from jQuery because I did not want to use jQuery but still have the backwards compatibility that jQuery does.
This function solves your question and at the bottom there are some examples on how to use it.
This functions uses the "module pattern" through the immediate function that will be run as soon as the script loads creating a method that will NOT polute the global scope but extend its functionality through a function to do what you wanted.
// I give it a name but it can also be anonymous
(function preloadedFunctions(){
// Preseted methods.
if(window.getComputedStyle){
window.getComputedStylePropertyValue = function(element, prop){
var computedStyle = window.getComputedStyle(element, null);
if(!computedStyle) return null;
if(computedStyle.getPropertyValue) {
return computedStyle.getPropertyValue(prop);
} else if (computedStyle.getAttribute) {
return computedStyle.getAttribute(prop);
} else if(computedStyle[prop]) {
return computedStyle[prop];
};
};
}
// jQuery JavaScript Library v1.9.0
// http://www.minhacienda.gov.co/portal/pls/portal/PORTAL.wwsbr_imt_services.GenericView?p_docname=6240612.JS&p_type=DOC&p_viewservice=VAHWSTH&p_searchstring=
// For IE8 or less
else if ( document.documentElement.currentStyle ) {
var rnumnonpx = new RegExp( "^(" + core_pnum + ")(?!px)[a-z%]+$", "i" ),
rposition = /^(top|right|bottom|left)$/,
core_pnum = /[+-]?(?:\d*\.|)\d+(?:[eE][+-]?\d+|)/.source;
window.getComputedStylePropertyValue = function(element, prop){
var left, rsLeft,
ret = element.currentStyle && element.currentStyle[ prop ],
style = element.style;
if ( ret == null && style && style[ prop ] ) {
ret = style[ prop ];
}
if ( rnumnonpx.test( ret ) && !rposition.test( prop ) ) {
left = style.left;
rsLeft = element.runtimeStyle && element.runtimeStyle.left;
if ( rsLeft ) {
element.runtimeStyle.left = element.currentStyle.left;
}
style.left = prop === "fontSize" ? "1em" : ret;
ret = style.pixelLeft + "px";
style.left = left;
if ( rsLeft ) {
element.runtimeStyle.left = rsLeft;
}
}
return ret === "" ? "auto" : ret;
};
};
})();
i.e.
1.-
var borderWidth = getComputedStylePropertyValue(document.getElementsByTagName("div")[0], "border-width");
console.log(borderWidth);
2.-
var div = document.getElementById("someID");
console.log(getComputedStylePropertyValue(div, "border-width"));
If somebody is still looking, this seems to be easiest way to do it with plain JS.
let border =
+getComputedStyle((document.getElementById("idOfYourElement")))
.borderTopWidth.slice(0, -2)
Explanation below:
document.getElementById("idOfYourElement") - Return our HTML element.
getComputedStyle - Return css attributes of chosen element as object.
.borderTopWidth - Corresponding attribute from getComputedStyle object (return array like this: ("10px")).
.slice(0, -2) - Cut the last 2 characters from our array so we get rid of px at the end.
And + at the start - Parse rest of our string, that contains number we want, to the integer.
You can try this:
var border = document.getElementById("yourDiv").clientWidth - document.getElementById("yourDiv").offsetWidth;
alert(border);
Note, that the value will be rounded to an integer. If fractional value is required, you need to use getComputedStyle instead (see other answers).
Very old question, but anyway...
This solution is plain JavaScript, and should work in older browsers too.
It measures the size of the element, with, and without borders.
The following example should work correctly if the borders around the element are all the same size.
If not, the procedure doesn't change much, you just have to set the borders equal to zero, one by one.
var ele=document.getElementById("content");
// measures the element width, WITH borders
var w=ele.offsetWidth;
var cssBackup=ele.style.cssText;
// sets the borders to zero
ele.style.border="0px";
// computes the border size
var bord=(w-ele.offsetWidth)/2;
// resets the css
ele.style.cssText=cssBackup;
alert(bord);
When left & right border has same width:
function getWidth(div) {
return (div.offsetWidth - div.clientWidth) /2
}
getWidth(document.querySelector('#content'))
According to W3Schools, this property is supported by major browsers. Thus you shouldn't have any difficulty in using it.
However, using a JavaScript framework like jQuery would always help you not worrying about trivial issues like this.
Works for me
let content = document.querySelector('#content');
// here 'borderWidth' is similar to element.style syntax
let contentBorderWidth = getComputedStyle(content).borderWidth; // 1px
// number, without 'px'
let contentBorderWidthNumber = parseFloat(getComputedStyle(content).borderWidth); // 1
// demo
content.innerHTML = contentBorderWidth +', '+ contentBorderWidthNumber;
// in your case, to alert
window.alert(contentBorderWidth +', '+ contentBorderWidthNumber);
div#content {
border: 1px solid skyblue;
}
<div id="content"></div>
More about getComputedStyle.
Related
I am looking for a way to retrieve the style from an element that has a style set upon it by the style tag.
<style>
#box {width: 100px;}
</style>
In the body
<div id="box"></div>
I'm looking for straight javascript without the use of libraries.
I tried the following, but keep receiving blanks:
alert (document.getElementById("box").style.width);
alert (document.getElementById("box").style.getPropertyValue("width"));
I noticed that I'm only able to use the above if I have set the style using javascript, but unable to with the style tags.
The element.style property lets you know only the CSS properties that were defined as inline in that element (programmatically, or defined in the style attribute of the element), you should get the computed style.
Is not so easy to do it in a cross-browser way, IE has its own way, through the element.currentStyle property, and the DOM Level 2 standard way, implemented by other browsers is through the document.defaultView.getComputedStyle method.
The two ways have differences, for example, the IE element.currentStyle property expect that you access the CCS property names composed of two or more words in camelCase (e.g. maxHeight, fontSize, backgroundColor, etc), the standard way expects the properties with the words separated with dashes (e.g. max-height, font-size, background-color, etc).
Also, the IE element.currentStyle will return all the sizes in the unit that they were specified, (e.g. 12pt, 50%, 5em), the standard way will compute the actual size in pixels always.
I made some time ago a cross-browser function that allows you to get the computed styles in a cross-browser way:
function getStyle(el, styleProp) {
var value, defaultView = (el.ownerDocument || document).defaultView;
// W3C standard way:
if (defaultView && defaultView.getComputedStyle) {
// sanitize property name to css notation
// (hypen separated words eg. font-Size)
styleProp = styleProp.replace(/([A-Z])/g, "-$1").toLowerCase();
return defaultView.getComputedStyle(el, null).getPropertyValue(styleProp);
} else if (el.currentStyle) { // IE
// sanitize property name to camelCase
styleProp = styleProp.replace(/\-(\w)/g, function(str, letter) {
return letter.toUpperCase();
});
value = el.currentStyle[styleProp];
// convert other units to pixels on IE
if (/^\d+(em|pt|%|ex)?$/i.test(value)) {
return (function(value) {
var oldLeft = el.style.left, oldRsLeft = el.runtimeStyle.left;
el.runtimeStyle.left = el.currentStyle.left;
el.style.left = value || 0;
value = el.style.pixelLeft + "px";
el.style.left = oldLeft;
el.runtimeStyle.left = oldRsLeft;
return value;
})(value);
}
return value;
}
}
The above function is not perfect for some cases, for example for colors, the standard method will return colors in the rgb(...) notation, on IE they will return them as they were defined.
I'm currently working on an article in the subject, you can follow the changes I make to this function here.
I believe you are now able to use Window.getComputedStyle()
Documentation MDN
var style = window.getComputedStyle(element[, pseudoElt]);
Example to get width of an element:
window.getComputedStyle(document.querySelector('#mainbar')).width
In jQuery, you can do alert($("#theid").css("width")).
-- if you haven't taken a look at jQuery, I highly recommend it; it makes many simple javascript tasks effortless.
Update
for the record, this post is 5 years old. The web has developed, moved on, etc. There are ways to do this with Plain Old Javascript, which is better.
Use getComputedStyle function, Computed style contains all the CSS properties set to an element. Even if do not set a property to an element. You will still find that property in the computed styles.
Example:
<style>
#Body_element {
color: green;
}
</style>
<body id="Body_element">
<script>
alert(getComputedStyle(Body_element).color)
</script>
</body>
This is a helper function if you want to get multiple style rules from the same element.
You pass it the element and the styles you want as arguments, and it will return their values
const convertRestArgsIntoStylesArr = ([...args]) => {
return args.slice(1);
}
const getStyles = function () {
const args = [...arguments];
const [element] = args;
let stylesProps = [...args][1] instanceof Array ? args[1] : convertRestArgsIntoStylesArr(args);
const styles = window.getComputedStyle(element);
const stylesObj = stylesProps.reduce((acc, v) => {
acc[v] = styles.getPropertyValue(v);
return acc;
}, {});
return stylesObj;
};
Now, you can use this function like this:
const styles = getStyles(document.body, "height", "width");
OR
const styles = getStyles(document.body, ["height", "width"]);
I am trying to make each div's background change color when 2 ids exist. it is not changing the color. I cannot figure out what I am doing wrong. I am brand new to javascript. I have an embedded stylesheet and dont know if the javascript will override the css.
Also, I know some PHP and want to 'echo' the variables throughout the program so that I can see what the string value is in order to debug my own code. what is the easiest way to do this?
function drop(ev){
ev.preventDefault();
var image = ev.dataTransfer.getData("content");
ev.target.appendChild(document.getElementById(image));
var mydiv = '';
for (var i=0;i<9;i++)
{
if ($('#target'.i).find('#answer'.i).length == 1)
{
mydiv = document.getElementById('target'+i);
mydiv.style.backgroundColor = '#00CC00';
}
else
{
mydiv = document.getElementById('target'+i);
mydiv.style.backgroundColor = '#FF0000';
}
}
}
I think your problem may be on this line you have . not + to build the id's correctly.
if ($('#target'.i).find('#answer'.i).length == 1)
so your code should be:
if ($('#target'+i).find('#answer'+i).length == 1)
Keeping in mind I'm no jQuery wizard, my first notion was something like this:
$('div[id^=target]').each(function() {
var el = $(this).find('div[id^=answer]').addBack();
el.css('backgroundColor', el.length > 1 ? '#00CC00' : '#FF0000');
});
...but then I noticed that unlike your example, I was changing both the parent and child div. Something like this might be closer to your intent:
$('div[id^=target]').css('backgroundColor', function () {
return $(this).find('div[id^=answer]').length ? '#00CC00' : '#FF0000';
});
You also could retain the for loop if that's your preference:
for (var i = 0; i < 9; ++i) {
$('div#target' + i).css('backgroundColor', function() {
return $(this).find('div#answer' + i).length ? '#00CC00' : '#FF0000';
});
}
...and, just for fun, something kinda esoteric:
$('div[id^=target]:has(div[id^=answer])').css('backgroundColor', '#00CC00');
$('div[id^=target]:not(:has(div[id^=answer]))').css('backgroundColor', '#FF0000');
Fiddle!
Your code should work (see fiddle) with the correct operator for concatenation, i.e. with + instead of ., however here are a few points you should bear in mind :
Point 1 :
Among all the i variables you're iterating over in your for loop, if there is no div with id equal to "target" + i you will end up in the following else block :
else
{
mydiv = document.getElementById('target'+i); // null
mydiv.style.backgroundColor = '#FF0000';
}
At that place mydiv will be null and mydiv.style will throw an error.
Point 2 :
It seems you used jQuery to find the answers elements, while you used document.getElementById, which is part of the DOM API, to select then the target element. It would have been more consistent to use jQuery there too.
Point 3 :
If you want to simply output the value of some variable you can use console.log, which will output in the javascript console of the browser. The console object is provided by the browser, therefore you may not have the console.log method, but if you are using an up to date browser there is a good chance you will have it.
To summarize, see this fiddle for an example that takes these points into account.
What I want to do is to set options into plugin like you normally would, but to also override those options with html5 data-attributes.
Here I have exactly that (jsfiddle), but there's a slight problem with that.
JSFiddle Code:
(function($){
$.fn.extend({
test: function(options) {
var defaults = {
background: null,
height: null
};
var options = $.extend( defaults, options);
return this.each(function() {
var o = options;
var obj = $(this);
var objD = obj.data();
// background
if ( !objD.background) {
var cBG = o.background;
}
else {
var cBG = objD.background;
}
// Opacity
if ( !objD.height) {
var cH = o.height;
}
else {
var cH = objD.height;
}
obj.css({
background: cBG,
height: cH
});
});
}
});
})(jQuery);
$(document).ready(function() {
$('.test').test({
background: 'red',
height: 400
});
});
The method that I'm using in the jsfiddle bloats the code so much, even with just 2 different options that are also using data.
Question is: How could I achieve same end result with less code, to determine wether or not data should be used?
Here is the part of the code from the jsfiddle, that determines wether or not to use data.
// objD is obj.data();
// background
if ( !objD.background) {
var cBG = o.background;
}
else {
var cBG = objD.background;
}
// Opacity
if ( !objD.height) {
var cH = o.height;
}
else {
var cH = objD.height;
}
obj.css({
background: cBG,
height: cH
});
I had a feeling that there might be a better solution, but I wasn't able to get it working, until now.
Of course I am no expert, but this seems to work and shortens the code even more, since it works the same way the plugin options normally do, it just adds the data-attribute in there.
Default - Initially use default options.
Custom - If set, use custom options to override defaults.
Data - If set, use data to override both.
http://jsfiddle.net/lollero/HvbdL/5/
o = $.extend(true, {}, options, $(this).data() );
Here's another jsfiddle example.
This one toggles the width of each box on click. The middle box has a data-attribute with bigger width value than the other divs.
As an extra example, here's the same thing with 1 more option added in to the mix.
Well, one common trick is the double-pipe "or" operator in your assignment. If the first value is true, the second one is ignored, since only one true statement is enough to make the entire expression true:
var cBG = objD.background || o.background;
var cH = objD.height || o.height;
In fact, if you don't need those variables anywhere else, just add the results into the last statement:
obj.css({
background: (objD.background || o.background),
height: (objD.height || o.height)
});
Your fiddle
Simplified example
Now if objD.background is any "falsey" value (such as null, undefined, false, zero, or the empty string), then o.background will automatically be used. If for some reason you don't want that, you should use the ternary operator with an appropriate test instead:
obj.css({
background: (objD.background!=undefined) ? objD.background : o.background,
height: (objD.height!=undefined) ? objD.height : o.height
});
An easy way would be using the jQuery HTML5data plugin from Mark Dalgleish. The pro side of this plugin is namespacing so your config will never clash with the config of some other plugin.
Let's say I have a DIV: <div></div> and I want to find out with JS what its line-height is. I know one can check the style attribute style.lineHeight, but I want to check the actual line-height, without it depending on the existence of a CSS rule.
Assuming the font family and font size are the same, both should output the same line-height:
<div>One line of text</div>
<div>Two <br /> Lines of text</div>
How can I get the line-height of an element with JavaScript?
The answer is actually using .clientHeight. As Gaby said, this is not really reliable/trustworthy. However, it is! Here:
function getLineHeight(el) {
var temp = document.createElement(el.nodeName), ret;
temp.setAttribute("style", "margin:0; padding:0; "
+ "font-family:" + (el.style.fontFamily || "inherit") + "; "
+ "font-size:" + (el.style.fontSize || "inherit"));
temp.innerHTML = "A";
el.parentNode.appendChild(temp);
ret = temp.clientHeight;
temp.parentNode.removeChild(temp);
return ret;
}
"Clone" the properties of your element into a new one, get the new's clientHeight, delete the temporary element, and return it's height;
Explained at quirksmode : http://www.quirksmode.org/dom/getstyles.html
example: http://www.jsfiddle.net/gaby/UXNs2/
function getStyle(el,styleProp)
{
var x = document.getElementById(el);
if (x.currentStyle)
var y = x.currentStyle[styleProp];
else if (window.getComputedStyle)
var y = document.defaultView.getComputedStyle(x,null).getPropertyValue(styleProp);
return y;
}
and use it like
getStyle('test', 'line-height' )
This solution works for me. It uses the value of the line-height property when it has been set explicitly or, when the value has not been set, it calculates the value by finding the difference in the height of the object when its contents are augmented by one line.
function calculateLineHeight (element) {
var lineHeight = parseInt(getStyle(element, 'line-height'), 10);
var clone;
var singleLineHeight;
var doubleLineHeight;
if (isNaN(lineHeight)) {
clone = element.cloneNode();
clone.innerHTML = '<br>';
element.appendChild(clone);
singleLineHeight = clone.offsetHeight;
clone.innerHTML = '<br><br>';
doubleLineHeight = clone.offsetHeight;
element.removeChild(clone);
lineHeight = doubleLineHeight - singleLineHeight;
}
return lineHeight;
}
See currentStyle for IE and getComputedStyle() for other browsers (also supported by IE9).
This is easy now with window.getComputedStyle.
function getLineHeight(el: HTMLSpanElement) {
return window.getComputedStyle(el).lineHeight;
}
It’s fairly complicated. I made an npm package for clamping text to a certain number of lines or a pixel height.
You can’t just check line-height. Sometimes that’s normal which is no help at all.
You can’t put the text in another element because it may receive different styles.
The most solid method I found was to remove all text from the element and measure its height. Then add a line and measure the height. the height the first line adds isn’t always the same as subsequent lines. Then add another line. The second and all subsequent lines all add the same amount.
My tool exposes a method called calculateTextMetrics() that which uses the above strategy and returns the resulting measurements.
https://github.com/tvanc/lineclamp#getting-text-metrics
One intuitive way (that doesn't require element reference) is to use selection and range APIs to get cursor height.
const range = window.getSelection().getRangeAt(0);
const height = (range.getClientRects()[0]).height;
ref: https://developer.mozilla.org/en-US/docs/Web/API/Element/getClientRects
This is the best way to me. No error for me so far
function getLineHeight(element) {
oldHtml = element.innerHTML
element.innerHTML = "A"
lineHeight = element.offsetHeight
element.innerHTML = oldHtml
return lineHeight }
In some browsers (namely, Firefox) the getComputedStyle().getPropertyValue() doesn't report anything for shorthand CSS, like border. Is there a non-specific-code way of getting these shorthand CSS values? I've considered making a whitelist of shorthand CSS and their respective longhand CSS values. But I realize doing that would be both a big pain and a non-forward-compatible design.
I'm wondering, what do you want to do with a string like border: 1px solid #000?
Say you want to reproduce an elems border in order to copy it copyStyle(el2, el, "border"):
// Copies a set of styles from one element to another.
function copyStyle(dest, source, shorthand) {
var computed = window.getComputedStyle(source, null);
for (var i = computed.length; i--;) {
var property = camelize(computed[i]);
if (property.indexOf(shorthand) > -1) {
console.log(property)
dest.style[property] = computed[property];
}
}
}
// prototype.js
function camelize(text) {
return text.replace(/-+(.)?/g, function (match, chr) {
return chr ? chr.toUpperCase() : '';
});
}
Comparing if two element's given set of styles matches can be done in the same manner. Other than that, I really can't see the use a string, which should be parsed if you want to compute anything with it.