Set and get CSS styles of elements

Get the computed style properties or set CSS properties for an element.

The getComputedStyle() method (IE < 9: currentStyle property) corresponds to the rendered on-page style of an element after all stylesheets were applied. It can be accessed as follows:

var el = document.querySelector('div');

// getComputedStyle for modern browsers, currentStyle for IE
var style = window.getComputedStyle ? getComputedStyle(el, null) : el.currentStyle;

// reading properties

// reading properties containing hyphens

Setting style properties is done directly via the style property of an element:

var el = document.querySelector('div'); = 'green'; = 'none';['border-radius'] = '5px';

Multiple styles can be set at once by use of the cssText property: += 'background: green, display: none;';

Note: The new style string is appended to the existing one (+=). Current style properties are overwritten and normalized. When overwriting the whole cssText, all previously set styles are discarded.

However, this method is rather slow and therefore it's better to use instead a little helper for setting multiple styles by an object of key/value pairs:

function css(el, styles) {
for (var property in styles)[property] = styles[property];

// example
var el = document.querySelector('div');
css(el, { background: 'green', display: 'none', 'border-radius': '5px' });

This helper function corresponds to jQuery's $.css(obj) method.