javascript: Regex replace certain class names with JavaScript from a html document

I am trying to remove all the class names that end with an underscore. So:


<div class="foo bar_ baz boo_ fa"> </div>

would output:


<div class="foo baz fa"> </div>

I am trying to do this in JavaScript and so far I can do it if the input only contains the string without other stuff:


```Node.js
var input = "foo bar_ baz boo_ fa";
input = input.replace(/(\w*[^ ])(?=_)(_)/g, "");

outputs:


foo  baz  fa

I am guessing that I am not using look ahead correctly. I wish I could something like:

input = input.replace(/class\s*=\s*["'](\w*[^ ])(?=_)(_)/g, "");

Program's overall purpose:

The purpose of the script is to read the html document and remove the "bad" class names from the whole document...

javascript