Скачать или смотреть How to Add a Key/Value Pair to a JavaScript Object

Summary: Learn how to easily add a key/value pair to a JavaScript object with various methods including dot notation, bracket notation, and the Object.assign() method.
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Adding a key/value pair to a JavaScript object is a common task in web development. There are several methods to achieve this, each with its own use cases and benefits. Below, we'll explore these methods in detail.

Using Dot Notation

Dot notation is the simplest and most common way to add a key/value pair to an object. This method is straightforward and easy to read.

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In this example, the key key is added to the object obj with the value "value".

Using Bracket Notation

Bracket notation allows you to add a key/value pair to an object using a variable or a string that represents the key. This method is particularly useful when the key is dynamic or contains special characters.

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You can also use bracket notation for keys with spaces or special characters:

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Using Object.assign()

The Object.assign() method is used to copy all enumerable own properties from one or more source objects to a target object. This method can be used to add multiple key/value pairs to an object at once.

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You can also merge multiple objects:

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Using the Spread Operator

The spread operator (...) is another way to add key/value pairs to an object, creating a new object with the new properties.

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This method is especially useful when you need to keep the original object unchanged.

Summary

Each method to add a key/value pair to a JavaScript object has its own advantages:

Dot Notation: Simple and readable, best for static keys.

Bracket Notation: Flexible, suitable for dynamic keys or keys with special characters.

Object.assign(): Powerful for merging multiple objects or adding multiple key/value pairs at once.

Spread Operator: Ideal for creating new objects while keeping the original object unchanged.

Choose the method that best fits your use case to efficiently manage your JavaScript objects.