How to call class in JavaScript

测试关于class的调用

.aaa{ font-size:20px; color:red; } .bbb{ font-size:50px; color:green; }

var test=document.getElementById('test'); test.className='aaa'; test.className='aaa bbb';//因为aaa和bbb的样式相同，所以，bbb的样式会覆盖aaa的样式

function hasClass(element,className){ //判断是否存在类 return element.className.match(new RegExp('(\\s|^)'+className+'(\s|$)')); } //添加一个Class function addClass(element,className){ if(!hasClass(element,className)){ element.className+=' '+className; } } //删除一个Class function removeClass(element,className){ if(hasClass(element,className)){ element.className=element.className.replace (new RegExp('(\\s|^)'+className+'(\s|$)'),' '); } }