js determines the style className while adding class or deleting class_javascript techniques

Copy code The code is as follows:

function MyClass () {}
MyClass.hasClassName = function( element, className)
{
if (!element) return;
var elementClassName = element.className;
if (elementClassName.length == 0) return false;
//Use regular expressions Expression to determine whether there is a real class between multiple classes (processing of leading and trailing spaces)
if (elementClassName == className || elementClassName.match(new RegExp("(^|\s)" className "(\s |$)")))
return true;
return false;
};
MyClass.addClassName = function(element, className)
{
if (!element) return ;
var elementClassName = element.className;
if (elementClassName.length == 0)
{
element.className = elementClassName;
return;
}
if ( elementClassName == className || elementClassName.match(new RegExp("(^|\s)" className "(\s|$)")))
return;
element.className = elementClassName " " className;
};
MyClass.removeClassName = function(element, className)
{
if (!element) return;
var elementClassName = element.className;
if (elementClassName.length == 0) return;
if(elementClassName == className)
{
element.className = "";
return;
}
if (elementClassName.match(new RegExp ("(^|\s)" className "(\s|$)")))
element.className = elementClassName.replace((new RegExp("(^|\s)" className "(\s| $)"))," ");
};