I have a div whose id is `divId` and I have written a JS script through which I am highlighting the "this" keyword.  
Here is the JS code  

```
            var regex = new RegExp('this',"gi");
     document.getElementById("divId").innerHTML=document.getElementById("divId").
    innerHTML.replace(regex, function(matched) 
{return '<span class=\'highlight\'>' + matched + '</span>';})

```

and here is the div  

```
This is the text This is the text This is the text This is the text 
This is the text This is the text This is the text This is the text 
This is the text This is the text This is the text This is the text 

```

Now I want to create a button on which I click and `highlight` class has been removed.I have tried this `document.getElementById("divId").className = ""` but it didn't work.As I am new to JS so now after my efforts now I am passing this problem to SO experts.How can I remove the class from all `this` word inside a div  
Any suggestions?