css - RemoveClass using JavaScript -

i'm trying add/remove class using javascript. (please don't post jquery, because that's irrelevant.) came upon this answer, suggested using regular expression remove class. here's code:

function removeclass(ele, cls) {     if (hasclass(ele, cls)) {         var reg = new regexp('(\\s|^)' + cls + '(\\s|$)');         ele.classname = ele.classname.replace(reg, ' ');     } } 

i'm going adding , removing same class. problem is, how ever many times that, that's how many spaces added class name. example, if add , remove class 5 times, there 5 spaces between 2 class names.

how can prevent spaces coming?

codepen

code snippet

var mydiv = document.getelementbyid('mydiv'),    par = document.getelementbyid('par');    mydiv.addeventlistener('click', function() {    if (hasclass(mydiv, 'trythis')) {      removeclass(mydiv, 'trythis');    } else {      addclass(mydiv, 'trythis');    }    console.log(mydiv.classname);  });        function hasclass(ele, cls) {    return ele.classname.match(new regexp('(\\s|^)' + cls + '(\\s|$)'));  }    function addclass(ele, cls) {    if (!hasclass(ele, cls)) ele.classname += " " + cls;  }    function removeclass(ele, cls) {    if (hasclass(ele, cls)) {      var reg = new regexp('(\\s|^)' + cls + '(\\s|$)');      ele.classname = ele.classname.replace(reg, ' ');    }  }

#mydiv {    width: 100px;    height: 100px;    background-color: green;  }  .trythis {    border: 2px solid orange;  }

<div id="mydiv" class="hello">click me</div>  <p id="par"></p>

there's 2 solutions. first (and easiest) use classlist. downfall solution won't able keep support browsers older implementation.

as second solution, keeps support old browsers , extends off regex solution, i'd suggest passing function replace checks if both sides of class name whitespace. if are, return ' ' otherwise return ''.

function removeclass(ele, cls) {   if (hasclass(ele, cls)) {     var reg = new regexp('(\\s|^)' + cls + '(\\s|$)');     ele.classname = ele.classname.replace(reg, function(match) {       if (match.match(/^\s.+\s$/) !== null) {         return ' ';       } else {         return '';       }     });   } } 

edit: there's option of using shim, sham, shiv, polyfill, etc.