Dynamically add, delete class style

function hasClass (obj, cls) { // class located in a word boundary pattern is determined whether class already exists 
return obj.className.match (new RegExp ( '( \\ s | ^)' + cls + '(\\ s | $ ) ')); 
} 
// class added to the obj 
function. addClass (obj, CLS) { 
IF (this.hasClass (obj, CLS)) {! 
obj.className = +' '+ CLS; 
} 
} 
// remove obj corresponding class 
function removeClass (obj, CLS) { 
IF (hasClass (obj, CLS)) { 
var new new REG = the RegExp ( '(S \\ | ^)' + + CLS '(S \\ | $)'); 
= obj.className.replace obj.className (REG, ''); 
} 
}