How to select all tag and register onclick event?

Question

I am trying to select all the tags in the page and register onclick even to them.

My codes:

document.getElementsByTag         


        

Answer 1

You're setting the onclick attribute to the array of elements, not to each element individually like you need. Also, you're defining show after you've used it.

var elts = document.getElementsByTagName('a');
var show = function() { alert('hahahha'); }
for (var i = elts.length - 1; i >= 0; --i) {
    elts[i].onclick = show;
}

It's more efficient to iterate backwards through the array than to test elts.length each time through. If you need to iterate forward, store the array length in a variable for better efficiency.