Preventing JavaScript Files from Loading Multiple Times

Michael Kennedy on Technology

This post is about ensuring that you do not execute a particular JavaScript file more than one time. Let’s start by asking:

What happens if you link to a js file twice in your page?

Here is a contrived example.

Notice that we are including bad-example.js twice. Do modern browsers somehow realize they loaded this file already and skip this? Not yet, as we’ll see!

Imagine bad-example.js had this code in it.

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