How to Extract Given Property Values from Objects as Array in JavaScript?

When working with data in JavaScript, it’s common to handle arrays of objects, such as user profiles, product lists, or API responses. Often, you need to extract property values from an array of objects in JavaScript for display, calculations, or filtering. Whether you’re looking to extract values from an object array or get property from object array, the map() method provides a clean and efficient solution. Developers frequently use a map to get values from an array of objects to transform structured data into simple arrays of specific property values.

Table of Contents:

• Understanding of How to Extract Values From Objects
• JavaScript Methods to Extract Object Property Values
  • Method 1: Using map() to Extract Property Values
  • Method 2: Extract Property Values Using reduce()
  • Method 3: Use for…of Loop for Property Extraction
  • Method 4: Extract Values Using forEach() Loop
• Performance Comparison of map(), reduce(), forEach(), and for…of loop
• Handling Edge Cases While Extracting Values
  • How to Handle Missing Properties in JavaScript Object Array?
  • Dealing with Empty Arrays When Extracting Values
• Real-World Use Cases To Get Object Property Values as Array in JavaScript
• Conclusion

Understanding of How to Extract Values From Objects

The problem is to get the given property values from objects as an array in JavaScript. But, before knowing more about the methods, let’s first understand the problem with the help of an example.

Input:

Expected Output:

["IntellipaatLearner1", "IntellipaatLearner2", "IntellipaatLearner3"]

Explanation: You have an array of objects, each of which represents an Intellipaat Learner with three properties: id, name, and age. The problem is that you need to extract only the name property from each object and print the result in the form of an array of names.

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JavaScript Methods to Extract Object Property Values

Let us explore each method for extracting a specific property as an array from an array of objects:

Method 1: Using map() to Extract Property Values

The map to get values from array of objects. It is the simplest way to get values from an array of objects in the form of an array. It creates a new array by applying a function to each element of the original array.

Example:

Output:

Explanation: In this example, the map is used to get values from array of objects. It will return a new array with the desired name values.

When Not to Use map()?

1. When doing side effects only:
   If your goal is to trigger side effects (such as modifying the DOM or updating a variable), use forEach(), as map() is intended for pure transformations.
2. When you don’t need the returned array:
   map() always returns a new array. If you’re not using that result, it’s better to use forEach() or a loop.
3. When you’re not transforming data:
   If you’re just performing an action on each item (like logging or updating something). map() is not the right choice.
4. When you want to filter items:
   map() should not be used to remove items. Use filter() instead when you want only certain elements.
5. When working with async/await:
   map() doesn’t handle await properly inside its callback. Use a for…of loop or Promise.all for asynchronous logic.

Method 2: Extract Property Values Using reduce()

The reduce() method is also used to get the value from an array of objects. It helps you to collect values into a single result (array in this case).

Example:

Output:

Explanation: In this example, you’re using the reduce() method for extracting values from the array of objects. Here, you start with an empty array [], iterate over each element of the array of objects (obj), and print the final accumulated array containing only names.

Method 3: Use for…of Loop for Property Extraction

A for…of loop can be used to iterate over the array of objects and push the required values into a new array.

Example:

Output:

Explanation: It is the traditional method for getting values from an array of objects and is more readable for beginners. 

Method 4: Extract Values Using forEach() Loop

The forEach() method is another way to iterate over the array. But not recommended for extracting values. It doesn’t return a new array.

Example:

Output:

Explanation: In this example, forEach() is used to extract the values from an array of objects. It is easy to use but less recommended.

Performance Comparison of map(), reduce(), forEach(), and for…of loop

Performance can be crucial when dealing with large datasets. Here is the comparison between each of the methods used to extract values in the form of an array from the array of objects:

Handling Edge Cases While Extracting Values

While extracting values from an array of objects and displaying them in the form of an array, you might get errors because of the following edge cases. Let’s discuss them one by one:

How to Handle Missing Properties in JavaScript Object Array?

What can you do if some of the objects do not have the required property?

Example:

Output:

Explanation: In this example, the object with id:2 has a missing name value. Thus, the .map() method iterates over the array and prints ‘unknown’ if it does not get any value as a name.

Dealing with Empty Arrays When Extracting Values

If an array of objects is empty, then these methods return an empty array as output.

Example:

const emptyArray = [];
const result = emptyArray.map(item => item.name);
console.log(result);

Output:

Explanation: In this example, an empty array is there, and iterating over an empty array gives you an empty array back as output.

Real-World Use Cases To Get Object Property Values as Array in JavaScript

Use Case 1: Extracting Usernames from API Response

When working with user data from an API, you often receive an array of user objects. You may need to extract just the usernames for display or processing. It will quickly display a list of usernames without loading full user details.

Explanation: Here, in this example, the JavaScript gets the property from object array and extracts the usernames from the data.

Use Case 2: Extracting Product Prices for Calculations

Suppose you’re working on a shopping cart feature and need to calculate the total cost from a list of products. Efficiently calculates totals for orders, taxes, or discounts.

Example:

Output:

Explanation: In this code, it calculates all the array values and gives the total as an output.

Use Case 3: Extracting Dates from Event Objects

Imagine you have a list of calendar events and want to generate an array of the event dates to highlight them in a calendar UI. Streamlines date handling for UI rendering or reminders.

Example:

Output:

Explanation: In this code, it fetched all the dates of the arrays in the given values.

Conclusion

Extracting specific property values from an array of objects is a fundamental skill in JavaScript, especially when working with structured data from APIs, forms, or databases. By using methods like map(), you can efficiently transform complex datasets into clean, usable arrays of values. Whether you need to extract a single property or prepare data for display, filtering, or computation, understanding this technique is essential for writing clean, maintainable code.

How to Extract Given Property Values from Objects as Array in JavaScript – FAQs