Extract specific properties from an array of objects in JavaScript

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By Bofu Agence MarketingMay 23, 20230 comments

Introduction

An array of objects in JavaScript is a collection of objects stored in a single variable.

Each object within the array can have its own set of properties.

Extracting specific properties allows you to isolate and manipulate relevant data from the array.

Accessing Object Properties in JavaScript To extract specific properties from objects, you need to understand how to access object properties in JavaScript.

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const books = [
  { id: 1, title: "Rich Dad Poor Dad", author: "Robert Kiyosaki" },
  { id: 2, title: "Limitless", author: "Jim Kwik" },
  { id: 3, title: "The Success Principles", author: "Jack Canfield" },
];

Two common ways to access object properties are dot notation and bracket notation.

Dot notation is a common approach to accessing the property.

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const obj = { id: 1, title: "Rich Dad Poor Dad", author: "Robert Kiyosaki" };

console.log(obj.title);

Bracket notation is used when the property name is stored in a variable or when the property name includes special characters or spaces.

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const obj = { id: 1, title: "Rich Dad Poor Dad", author: "Robert Kiyosaki" };

console.log(obj["title"]);

Iterating Through an Array of Objects Before we can extract specific properties from an array of objects, we need to iterate through the array to access each object.

There are multiple ways to iterate through an array in JavaScript.

Two commonly used methods are:

Case: You have an array of objects representing books. Now, you need to extract the titles of every book.

???? It is a real use-case, where we usually have an API that returns this type of data.

???? To extract specific properties, we can use different ways, like loops.

???? map() array method is more efficient in such cases (Simplicity, Performance & Readability)

Using loops like forEach:

You can use loops like forEach to iterate through each object in the array. You can retrieve the object and perform further operations.

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Using the map method:

The map method creates a new array by executing a provided function on each element in the calling array. It allows you to extract specific properties from each object and return them as a new array.

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Conclusion

In JavaScript, extracting specific properties from an array of objects is common. You can efficiently extract the desired properties by leveraging techniques like iterating through the array, using loops like forEach or map methods. These techniques provide flexibility and enable you to work with specific data points without modifying the original array.

FAQs

Is it possible to extract nested properties from objects within an array?

You can access nested properties using dot or bracket notation with the appropriate hierarchy.

What happens if the property I want to extract does not exist in some objects?

If the property does not exist in an object, accessing it will return undefined. You can handle such cases using conditional statements.

Can I modify the extracted properties and update the original array?

You can modify the extracted properties, but it will not update the original array.

Are there any performance considerations when extracting properties from large arrays?

When working with large arrays, performance can be a concern. Using efficient methods like map, reduce, or filter can help optimize the extraction process.