Ugly Duck

Obvious Javascript 'Injection' Fallback

December 4, 2020

Sometimes websites and web apps might require content to be “injected” via Javascript. I should mention that I am strongly against this practice - but often this kind of thing is out of one’s hands. So, the least I can do is setup these “injections” to have proper fallbacks for users who disable JS. You would be surprised how many developers build empty HTML elements with the assumption they will be filled via Javascript.

Our Hypothetical Project

Let’s pretend that we have a total tally that pulls in the number of current users using our fake SaaS app. We would do something like this:

HTML

Here we create an empty h2 tag that will update with the current number of users via js:

<main>
    <h2 class="total-tally"></h2>
</main>

Javascript

You’ll have to use your imagination here and assume that the totalTally variable pulls in the numbers dynamically via API:

var totalTally = "273,677" /* This would pull something dynamically in prod */
document.getElementsByClassName("total-tally")[0].innerHTML=totalTally;

The Problem

The big issue we have now occurs when a user visits this page without JS enabled. The h2 tag will remain empty and they won’t see anything. I know this seems like a very avoidable issue, but you would be surprised how often it actually happens on the web.

The (overly simple) Solution

The easiest way to avoid these types of empty tags - add static content. I know - mind blowing, right?

HTML (updated)

<main>
    <h2 class="total-tally">200,000+</h2>
</main>

You might be reading this and saying to yourself, “Wow! Thanks Captain Obvious!” and that’s a fair reaction. This is an obvious demo on purpose. If even one single reader learns to avoid leaving empty HTML tags that are solely dependent on Javascript injection, then I’d say this demo was a huge success.

Rule of thumb: don’t make assumption about your users. Play it safe.

~ fin ~