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Hiding a "N/A" value of a src attribute of an img tag from an API

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Hiding a 'N/A' value of a src attribute of an img tag from an API
Photo by USGS on Unsplash

Don't you hate it when you receive an image from an API and the value of the src attribute is "N/A" (or some other similar value)?

Well, that happened to me the other day. I was working on course content for my Dynamic Web 1 class I am teaching at the New York City College of Technology (City Tech in Brooklyn), and I noticed that there were quite a few responses from the OMDB API which contained placeholder images because there was no actual image available.

This kind of thing really uglifies an application, and I wanted to remove them from the response stream when present.

The solution is very simple really, and I have not come across it anywhere yet.

Anyway, all you have to do is figure out what the value of the img tag's src attribute is and then add the following to your CSS:

[src='N/A'] {
	display: none;
}

For the API I was working with, the img tag returned from the API contains the src attribute value of 'N/A', so it was simple to set its display property to 'none'.

Sometimes a broken img path is passed as the value to the src attribute, so those still appear with the alternate placeholder image. In cases like that, you have to use a bit of JavaScript. I use the following code to set the broken image's display property to 'none':

// remove img src broken links
document.addEventListener('DOMContentLoaded', function () {
	document.querySelectorAll('img').forEach(function (img) {
		img.onerror = function () {
			this.style.display = 'none'
		}
	})
})

The way that you can quickly check whether the code actually works or not is by adding an img tag to your html with a fake image, and then checking whether or not the placeholder image of 16w x 16h shows up or not on the page. For example, I added the following to my results.ejs page in my Node.js application:

<img src="alt.jpg" alt />

And the following showed up in my html Elements tab in the Developer Tools Console:

screenshot of altext image set to none

And the page looked like the following in the browser (no alternate default placeholder image):

screenshot of altext image successfully removed

So there are two scenarios one has to cover. First is when there is no image available, which can be solved with pure CSS. And the other is when the value of the image src attribute is a broken link. That has to be solved with JavaScript.

onerror property breakdown

onerror is a property of the GlobalEventHandlers and is an EventHandler that processes error events.

Error events are fired on various targets for various types of errors. In our case, it is due to a broken link or path passed as a value of an image src attribute.

When an image fails to load for whatever reason, an error event is fired on the img element that initiated the load, and the onerror() handler on the element is invoked.

Basically, I am setting the onerror property on the img element and initializing its value with an anonymous function. It is inside the body of this function that I set thestyle.display property to 'none'.

Now this approach works in Firefox and Chrome just fine. But when I went to check it in Safari, it did NOT work. A small placeholder image still appears. That's because Safari does not support completely the onerror property. I'm willing to stick with my solution for now anyway, as the occurrence is extremely low. If I had tried to replace the src attribute to "N/A" onerror, which would work in Safari, then I would end up with absolutely NO IMAGES. To learn more about which browsers are compatible with the onerror property, please visit quirksmode.org.

I will be embedding this episode of Plugging in The Holes along with a transcript in the form of a post on interglobalmedianetwork.com for your hearing and reading pleasure. Bye for now!

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