user3622460 user3622460 - 7 months ago 17
jQuery Question

Error while selecting allElementsByID and adding a class to them

Hello I'm trying to add a class to all of my elements on a webpage. The overall goal is to grab all the elements on a webpage and add in a class. The class containing a font size will be changed to hide a message.

I'm getting this error
Uncaught TypeError: Cannot set property 'innerHTML' of null

I've tried moving my script outside the body tag of my index.html but its still not working.

Another problem is I can't add a class to all of the IDs I'm selecting. I can add classes manually like

$("#iconLog").addClass("style"); //this works

but when I try to add a class like this

empTwo = "#" + temp; //where empTwo is a string that equals "#iconLog"
$("empTwo").addClass("style") //this does not work

I'll post my entire script below for reference

$(function() {

var hideMsg = "f";
var n = hideMsg.length;

var i;
var j;
var holder;
var hideHolder;

// on button click - hide msg
$('#btnHide').on('click', function() {

//grab all IDS ON WEBPAGE

var allElements = document.getElementsByTagName("*");
var allIds = [];
for (var i = 0, n = allElements.length; i < n; ++i) {
var el = allElements[i];
if ( {

for(var i = 0; i < allElements.length; ++i)
var temp = document.getElementById(allIds[i]).id;
document.getElementById("*").innerHTML = err.message;

tempTwo = "#" + temp;

//$("#iconLog").addClass("style") //this works
$("tempTwo").addClass("style"); //this does not work

for(i = 0; i < n; i++) {

//set var holder to first value of the message to hide
holder = hideMsg.charCodeAt(i);

for(j = 7; -1 < j; j--) {

//set hideHolder to holders value
hideHolder = holder;
//mask hideHolder to grab the first bit to hide
hideHolder = hideHolder & (1<<j);

//grab the first element ID

if(hideHolder === 0) {

// embed the bit
// bitwise &=

} else {
//embed the bit
// bitwise ^=



To add a class to all elements you don't need a for loop. Try this:


Same for setting the inner html of all elements. Try this:

$("*").html("Html here");