Understanding JavaScript Objects: Why Use Variable Names as Keys?

Dive into the intricacies of JavaScript object properties, and learn why variable names can be misleading when used as keys. Discover how to use computed property names for dynamic values.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Why is the object property using variable name as key instead of variable value?

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding JavaScript Objects: Why Use Variable Names as Keys?

When working with JavaScript and TypeScript, you might encounter scenarios where you need to use variable values as object keys. However, a common issue arises when you try to assign a variable's value as a key but find that the object stores the variable name instead. In this guide, we will explain this phenomenon, explore the solution, and provide examples to help clarify the concept.

The Problem

Imagine you have a Record<TableId, TableState> object, where TableId is defined as a string. You are attempting to set a key/value pair by using a variable to represent the key. However, the output shows the object storing the variable's name rather than its value. In your code, when trying to create a map in the following way:

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

You are actually creating an object that looks like this: {id: {…}}, instead of using the value stored in the variable id. This can be confusing and lead to bugs in your application.

The Solution

The key to resolving this issue lies in the use of computed property names in JavaScript/TypeScript. This allows you to dynamically define the names of object properties using square brackets. Here’s how to correctly set the key/value pair using the variable's value as the key:

Using Computed Property Names

Instead of using the following code:

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

You should use square brackets around id to dynamically capture its value:

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

With this change, the resulting object will correctly assign the value of the id variable as the key, resulting in {valueOfId: {…}}, where valueOfId is the actual dynamic value assigned to id.

Updated Code Example

Here is your updated React code snippet with the changes in action:

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

Summary

Understand the issue: Using a static key when defining an object will reference the variable name, not its value.

Use computed property names: Encapsulate the variable name in square brackets to ensure its value is used as the object key.

Refactor your code: Update existing object definitions to incorporate computed property names for accurate dynamic key assignment.

By following the steps outlined above, you can eliminate confusion and ensure your JavaScript and TypeScript code functions as intended. Remember, understanding object properties is crucial for writing efficient and bug-free code!