Understanding Variable Updates in JavaScript: Why Your Token Isn't Changing

Learn how variables work in JavaScript, why your token updates may not be reflected in requests, and how to properly manage your headers in your scripts.
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This video is based on the question https://stackoverflow.com/q/78252855/ asked by the user 'lfgan' ( https://stackoverflow.com/u/22460695/ ) and on the answer https://stackoverflow.com/a/78252890/ provided by the user 'Simon Lundberg' ( https://stackoverflow.com/u/1031253/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Variable Updates in JavaScript: Why Your Token Isn't Changing

If you’re new to JavaScript, dealing with variables can often be confusing. You might have a situation where you’re trying to update a token for API headers in your script, but the changes don’t seem to reflect in the requests you send. This common frustration happens to many beginners, and it stems from a fundamental concept in JavaScript that separates how primitive values and objects work.

The Problem: Token Not Updating

You might encounter code similar to this:

[[See Video to Reveal this Text or Code Snippet]]

In this scenario, even after you assign abc23token a new value (token2), the request still uses the initial value (token1). Why does this happen?

Understanding Variables in JavaScript

To grasp why your token isn’t updating, you need to understand how JavaScript treats variables.

1. Primitives versus Objects

JavaScript categorizes values into two primary types: primitives and objects.

Primitives include types such as:

Strings

Numbers

Booleans

When you assign a primitive value to a variable and then change the value of that variable, it doesn't alter the original value. It simply creates a new reference for the updated variable.

For example:

[[See Video to Reveal this Text or Code Snippet]]

In this example, b remains "hello" even after a is changed, because these are separate primitive values.

Objects, on the other hand, work differently. They are mutable, meaning their properties can change without affecting the reference itself.

For example:

[[See Video to Reveal this Text or Code Snippet]]

In this case, changing token does not affect obj.token because token is just a copy of the value from the object.

2. Applying This to Your Token Scenario

So, back to your code. The authorization header you defined initially uses the abc23token, which holds the value of token1. When you later assign abc23token to token2, this doesn’t retroactively change the headers object that you created earlier.

Solution: Redefining Headers

To ensure that your requests send the latest token value, you will need to redefine the headers after updating abc23token. Here’s how you can adjust your script:

[[See Video to Reveal this Text or Code Snippet]]

Key Takeaways

Understand the types of variables: Know when you’re dealing with primitives versus objects.

Redefine your headers: Whenever the token changes, you’ll need to recreate the headers to ensure the latest value is reflected.

Practice: The more you work with JavaScript, the more intuitive these concepts will become.

Remember, you’re not alone in feeling confused about variable assignments in JavaScript. This is a common hiccup, especially for beginners. Keep experimenting and learning!