Summary of method examples for obtaining various CSS style attributes in native javascript

The most familiar method for manipulating styles in native js is the Style object in the DOM. However, this method can only obtain and modify inline styles in html documents, and cannot operate non-inline styles (internal styles and external style sheets).

Get style

1. dom style

This method can only get inline styles:

var text = document.getElementById('text');
var textColor = text.style.color;

// 得到textColor的值为 '#000'

2. currentStyle

This method only applies to IE The browser is similar in form to element.style. The difference is that currentStyle is just like its name - the current style (the style after css is loaded), which returns the current final CSS attribute value of the element, including The styles in the internal style tag and the css files imported from outside.

Usage: element.currentStyle.property

For example, we want to get the width of the box with the id:

##

var boxWidth = document.getElementById('box').currentStyle.width;

// 得到boxWidth的值为 '200px'

3. getComputedStyle

getComputedStyle is a method that can obtain all ultimately used CSS property values ​​​​of the current element. What is returned is a CSS style declaration object ([object CSSStyleDeclaration]) and is read-only.

In terms of compatibility, basic support: Chrome, Firfox, IE9, Opera, Safari

Usage: getComputedStyle (element, pseudo-class). Attribute, if the second parameter is not a pseudo-class Set it to null.

var el = document.getElementById("box");
var style = window.getComputedStyle(el , ":after");

Come and encapsulate a general function to get the style

In order to be applicable to all major mainstream browsers, let’s write a function:

// 这个函数需要传递两个参数：元素对象和样式属性名称

function getStyle(el, styleName) {

 if( el.currentStyle ) {
 
 // for IE
 return el.currentStyle[styleName];
 
 } else {
 
 // for peace
 return getComputedStyle(el, false)[styleName];
 }
 
}

Then call this function to get the width of the box:

var box = document.getElementById("box");

var boxWidth = getStyle(box, 'width');

This function does not take into account the pseudo The related operations of the class can be extended as needed~

What is the difference between getComputedStyle and style?

Since they both get the value of the style attribute, what is the difference between them:

Read-only and writable The

getComputedStyle method is read-only and can only get the style but not set it, but

element.style can both read and write.

The scope of objects obtained

The getComputedStyle method obtains all CSS attribute objects that are ultimately applied to the element (even if there is no CSS code, the default ancestor eight generations will be are displayed); and element.style can only get the CSS style in the element's style attribute. Therefore, for a bare element e388a4556c0f65e1904146cc1a846bee, the length attribute value (if any) returned by the getComputedStyle method in the object is 190+ (according to my tests, FF: 192, IE9: 195, Chrome: 253, the results may be different in different environments), And element.style is 0.

Set style

1. dom style

This is not necessary Let’s talk, for example, change the background color of the element to red:

var el = document.getElementById('box');
el.style.backgroundColor = 'red';

2. cssText attribute

cssText The essence is to set the style attribute value of the HTML element. It is a textual representation of a set of style properties and their values. This text is formatted as a CSS stylesheet, with the curly braces surrounding the attribute and value element selectors removed.

Its usage is similar to innerHTML:

document.getElementById("d1").style.cssText = "color:red; font-size:13px;";

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