Input type password show password

Question

I followed some tutorials to get the display input Like this one here :http://jsfiddle.net/cj3kmxL4/1/ But when I run on my pc it gives the following error:

Code:

Answer 1

It was only for an onloadm because the code was trying to get the value before the DOM upload

window.onload=function(){
 var input = document.querySelector('#input input');
                var img = document.querySelector('#input img');
                var visivel = false;
                img.addEventListener('mousedown', function () {
                visivel = true;
                input.type = 'text';
                });
                window.addEventListener('mouseup', function (e) {
                if (visivel) visivel = !visivel;
                input.type = 'password';
                });
            }