You got an extra } to many as seen below:
var nav = document.getElementsByClassName('nav-coll');
for (var i = 0; i < button.length; i++) {
nav[i].addEventListener('click',function(){
console.log('haha');
} // <-- REMOVE THIS :)
}, false);
};
A very good tool for those things is jsFiddle. I have created a fiddle with your invalid code and when clicking the TidyUp button it formats your code which makes it clearer if there are any possible mistakes with missing braces.
DEMO - Your code in a fiddle, have a play :)