Use JS to implement jQuery's addClass, removeClass, and hasClass functions_javascript skills

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Copy code The code is as follows:

function addClass(obj, cls){
var obj_class = obj.className,//Get class content.
Blank = (obj_class != '') ? ' ' : '';//Determine whether the obtained class is empty, if not, add a 'space' in front.
added = obj_class blank cls;//Combine the original class and the class that needs to be added.
Obj.className = added;//Replace the original class.
}

function removeClass(obj, cls){
var obj_class = ' ' obj.className ' ';//Get the class content and add a space at the beginning and end. ex) 'abc bcd' -> ' abc bcd '
obj_class = obj_class.replace(/(s )/gi, ' '),//Replace the extra null character with a space. ex) ' abc bcd ' -> ' abc bcd '
Removed = obj_class.replace(' ' cls ' ', ' ');//Replace the class with spaces at the beginning and end of the original class. ex) ' abc bcd ' -> 'bcd '
Removed = removed.replace(/(^s )|(s $)/g, '');//Remove leading and trailing spaces. ex) 'bcd ' -> 'bcd'
Obj.className = removed;//Replace the original class.
}

function hasClass(obj, cls){
var obj_class = obj.className,//Get class content.
Obj_class_lst = obj_class.split(/s /);//Convert cls into an array by splitting the null character.
x = 0;
for(x in obj_class_lst) {
If(obj_class_lst[x] == cls) {//Loop the array to determine whether it contains cls
             return true;
}
}
Return false;
}