How to make JavaScript work when button is pressed?

Steps to add a event :

1).Add selector (either class or id) to the element (ex: <--button class="classname">test<--/button-->)

2).In document ready - Add on click event and write the related code inside it.

Note : Add Jquery.js in HTML page

 $( document ).ready(function() {
    $('.classname').on('click',function(){
    /** write related code inside **/
      yourfunc();
    });
 });

function yourfunc(){
alert('this is the other function');
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button class="classname">test</button>

you just cant use .click() as some browser wont pick it up. please test after using .

   <script type="text/javascript">
function performClick(elemId) {
   var elem = document.getElementById(elemId);
   if(elem && document.createEvent) {
      var evt = document.createEvent("MouseEvents");
      evt.initEvent("click", true, false);
      elem.dispatchEvent(evt);
   }
}
</script>
<a href="#" onclick="performClick('theFile');">Open file dialog</a>
<input type="file" id="theFile" />

  <div id="btn">
               <a href='dg-quiz-maker.js' class='button'>ATTEMPT A QUIZ</a>
               </div>

See the Plunker code:

http://plnkr.co/edit/YB09Puxc7qJmeW8V86nR?p=preview`

In this case the script file is in same directory with HTML

What you can do is make a javascript function and call it on click like this:

<div id="btn">
   <a href='#' onclick="myFunc();" class='button'>ATTEMPT A QUIZ</a>
</div>

<script>
function myFunc(){
   alert('test');
}
</script>

Or you can include functions from js files like this:

<script src="dg-quiz-maker.js"></script>

First of All, Opening a JS file is kind of weird thing , but still if u want to,The "href" property of <a> tag should be a proper(or relative) uri path of the file placed in your directory.

I hope it will solve your purpose.