How Do You Work With Dynamic Object Keys in JavaScript?

Accessing and Modifying Dynamic Object Keys with JavaScript

Creating dynamic keys in JavaScript objects is crucial for manipulating data dynamically. Understanding this concept allows for greater flexibility in your code.

Using Square Brackets

To access or modify a property with a dynamic key, use square brackets ([]) along with the key name enclosed in quotes:

<code class="javascript">jsObj['key' + i] = 'example' + 1;</code>

This syntax allows you to construct keys dynamically based on the value of i.

Understanding the Role of Arrays

Although arrays inherit from the Object prototype in JavaScript, not all objects are arrays. Arrays maintain the length property, which adjusts dynamically based on numeric property names. However, this behavior is unrelated to the operation of the square bracket operator.

Setting Property Values

When setting values for properties with numeric keys in arrays, the length property is updated accordingly. However, this does not apply to plain objects, where setting a property with a numeric key does not affect the length property.

Limitations with Array Instances and JSON Serialization

Note that array instances serialized to JSON only include properties with numeric names. Properties added using non-numeric keys will be lost during serialization.

ES2015 Computed Property Names

In ES6, computed property names offer an alternative for creating dynamic keys:

<code class="javascript">var key = 'DYNAMIC_KEY',
    obj = {
        [key]: 'ES6!'
    };</code>

This allows you to use variables or expressions to define property keys more easily and concisely.

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