js judges the style className and add class or delete class

function MyClass () {}
= function(element, className)
{
if (!element) return;
var elementClassName = ;
if ( == 0) return false;
//Use regular expressions to determine whether there is a real class between multiple classes (processing of front and back spaces)
if (elementClassName == className || (new RegExp("(^|\\s)" + className + "(\\s|$)")))
return true;
return false;
};
= function(element, className)
{
if (!element) return;
var elementClassName = ;
if ( == 0)
{
= elementClassName;
return;
}
if (elementClassName == className || (new RegExp("(^|\\s)" + className + "(\\s|$)")))
return;
= elementClassName + " " + className;
};
= function(element, className)
{
if (!element) return;
var elementClassName = ;
if ( == 0) return;
if(elementClassName == className)
{
= "";
return;
}
if ((new RegExp("(^|\\s)" + className + "(\\s|$)")))
= ((new RegExp("(^|\\s)" + className + "(\\s|$)"))," ");
};