原生js 查找 添加 删除 指定元素的class

window.onload = function(){var gaga = document.getElementById( "gaga" );addClass( gaga,"gaga1" ) addClass( gaga,"gaxx" );removeClass( gaga,"gaga1" )removeClass( gaga,"gaga" )function hasClass( elements,cName ){return !!elements.className.match( new RegExp( "(\\s|^)" + cName + "(\\s|$)") );           // ( \\s|^ ) 判断前面是否有空格  （\\s | $ ）判断后面是否有空格  两个感叹号为转换为布尔值 以方便做判断};function addClass( elements,cName ){if( !hasClass( elements,cName ) ){elements.className += " " + cName;};};function removeClass( elements,cName ){if( hasClass( elements,cName ) ){elements.className = elements.className.replace( new RegExp( "(\\s|^)" + cName + "(\\s|$)" )," " );  // replace方法是替换};};};