Introduction
Understanding how to effectively copy objects in JavaScript is a fundamental skill for any developer. Whether you’re building complex data structures or simply passing data between functions, object copying is essential. In this guide, we’ll explore the intricacies of shallow and deep copies, exploring their differences, use cases, and implementation techniques. By the end, you’ll have a solid grasp of object copying and be able to confidently choose the appropriate method for your specific needs.
Shallow Copy
A shallow copy creates a new object but shares references to the original object’s properties. This means that changes made to the copied object will also affect the original object. While efficient, shallow copies can lead to unexpected behavior if not used carefully.
How Shallow Copies Work:
When you perform a shallow copy, a new object is created, and its properties are assigned the same values as the original object’s properties. However, these values are actually references to the original object’s data. As a result, any modifications to the copied object’s properties will also affect the original object.
Creating Shallow Copies:
JavaScript provides two primary methods for creating shallow copies:
- Object.assign():
const originalObject = { a: 1, b: { c: 2 } };
const shallowCopy = Object.assign({}, originalObject);This method creates a new object and copies the enumerable own properties from one or more source objects to the target object.
2. Spread Operator:
const originalObject = { a: 1, b: { c: 2 } };
const shallowCopy = { ...originalObject };The spread operator creates a new object and copies the enumerable own properties from the right-hand side object to the left-hand side object.
Use Cases for Shallow Copies:
Shallow copies are suitable when you need to create a new object that shares some properties with the original object, but you don’t expect to modify those shared properties. For example, creating a configuration object based on a default configuration.
Deep Copy
A deep copy creates a new object and recursively copies all properties, including nested objects and arrays. This ensures that changes made to the copied object do not affect the original object.
How Deep Copies Work:
To achieve a deep copy, you need to create a new object and recursively copy all properties, including nested objects and arrays. This process involves creating new instances of each object and array, effectively isolating the copied data from the original.
Creating Deep Copies:
There are several methods for creating deep copies:
- JSON.parse(JSON.stringify()):
const originalObject = { a: 1, b: { c: 2 } };
const deepCopy = JSON.parse(JSON.stringify(originalObject));This method serializes the original object into a JSON string and then parses it back into a new object. While simple, it has limitations, such as not handling functions, undefined values, and circular references.
2. Lodash cloneDeep():
const _ = require('lodash');
const originalObject = { a: 1, b: { c: 2 } };
const deepCopy = _.cloneDeep(originalObject);Lodash provides a robust cloneDeep function that handles complex object structures, including circular references and custom objects.
Assigning Properties to Objects
In addition to creating copies, you often need to assign properties to existing objects. JavaScript provides several ways to achieve this:
- Direct Assignment:
const object = {};
object.property1 = 'value1';
object['property2'] = 'value2';2. Object Literal:
const object = {
property1: 'value1',
property2: 'value2'
};3. Object.assign():
Object.assign() can be used to create a new object based on an existing one while also adding new properties to it.
const object = {};
Object.assign(object, { property1: 'value1', property2: 'value2' });Use Cases for Deep Copies:
Deep copies are essential when you need to create an independent copy of an object and its nested structures. This is common in scenarios where you want to modify the copied object without affecting the original, such as passing data to functions or storing data in state management.
| Feature | Shallow Copy | Deep Copy |
| Object Creation | Creates a new object | Creates a new object and recursively copies properties |
| Property Values | References original object’s properties | Creates new instances of properties |
| Performance | Generally faster | Slower due to recursive copying |
| Use Cases | Sharing properties without modification | Independent copy of object and nested structures |
Advanced Techniques
While Object.assign, spread operator, JSON.parse(JSON.stringify), and lodash cloneDeep are commonly used for object copying, there are other techniques to explore:
- Custom Cloning Functions: You can create your own cloning functions to handle specific object structures or perform additional logic during the copying process.
- structuredClone: This experimental API provides a way to create structured clones of objects, including support for more complex data types.
Custom Cloning Functions
A custom cloning function is a function that you write yourself to copy objects in a specific way. This can be useful if you need to copy objects that have specific properties or methods, or if you need to perform additional logic during the copying process.
Here is an example of a custom cloning function that copies objects recursively:
function cloneObject(obj) {
if (typeof obj !== 'object' || obj === null) {
return obj;
}
const newObj = Array.isArray(obj) ? [] : {};
for (const key in obj) {
if (obj.hasOwnProperty(key)) {
newObj[key] = cloneObject(obj[key]);
}
}
return newObj;
}
This function takes an object as input and returns a new object that is a deep copy of the original object. The function recursively copies each property of the object, including nested objects and arrays.
Structured Clone
The structuredClone function is an experimental API that provides a way to create structured clones of objects. This can be useful if you need to copy objects that have specific properties or methods, or if you need to perform additional logic during the copying process.
Here is an example of using the structuredClone function to copy an object:
const originalObject = {
name: 'John Doe',
address: {
street: '123 Main St',
city: 'New York',
state: 'NY'
}
};
const clonedObject = structuredClone(originalObject);This code will create a new object called clonedObject that is a deep copy of the original object. The structuredClone function can also be used to copy functions and other complex data types.
Additional Considerations
When using custom cloning functions, it is important to consider the performance implications of your function. Recursive functions can be slow for large objects, so it is important to optimize your function for performance.
The structuredClone function is still an experimental API, so its support may vary between browsers. It is important to test your code with different browsers to ensure compatibility.
Best Practices
- Understand the difference between shallow and deep copies.
- Choose the appropriate copying method based on your specific requirements.
- Be aware of performance implications, especially when dealing with large objects.
- Consider using immutable data structures to avoid accidental modifications.
- Test your code thoroughly to ensure correct object copying behavior.
Conclusion
Mastering object copying in JavaScript is crucial for building robust and efficient applications. By understanding the concepts of shallow and deep copies, you can effectively manage object data and prevent unexpected side effects.Experiment with different techniques, consider performance implications, and follow best practices to optimize your object copying strategies.
Subscribe
Enter your email below to receive updates.
Share the article with your friends
Exactly what I was searching for, appreciate it for posting.
What i do not understood is if truth be told how you’re not really a lot more smartly-favored than you might be now. You are so intelligent. You recognize therefore significantly on the subject of this subject, made me personally imagine it from numerous numerous angles. Its like men and women don’t seem to be fascinated unless it is something to do with Girl gaga! Your personal stuffs nice. Always maintain it up!
As a Newbie, I am always searching online for articles that can aid me. Thank you
Thank you for sharing superb informations. Your website is very cool. I’m impressed by the details that you’ve on this web site. It reveals how nicely you understand this subject. Bookmarked this website page, will come back for more articles. You, my friend, ROCK! I found simply the information I already searched everywhere and just couldn’t come across. What an ideal website.
WONDERFUL Post.thanks for share..extra wait .. …
I really like looking at and I think this website got some truly useful stuff on it! .
I think this site contains some very good information for everyone. “He is able who thinks he is able.” by Buddha.
Appreciate it for this post, I am a big fan of this internet site would like to go on updated.
Very nice post. I just stumbled upon your weblog and wanted to say that I’ve really enjoyed surfing around your blog posts. After all I’ll be subscribing to your rss feed and I hope you write again soon!
Hi there! Do you know if they make any plugins to safeguard against hackers? I’m kinda paranoid about losing everything I’ve worked hard on. Any suggestions?
Real clear web site, thanks for this post.
you are really a good webmaster. The web site loading speed is amazing. It seems that you’re doing any unique trick. Also, The contents are masterwork. you’ve done a magnificent job on this topic!
Great blog! I am loving it!! Will come back again. I am taking your feeds also
I have been exploring for a bit for any high quality articles or blog posts in this kind of area . Exploring in Yahoo I finally stumbled upon this site. Reading this info So i?¦m happy to convey that I have an incredibly excellent uncanny feeling I came upon exactly what I needed. I so much surely will make sure to do not overlook this website and provides it a look regularly.
Thanks for every other informative site. Where else may I get that type of information written in such a perfect method? I’ve a challenge that I’m just now operating on, and I’ve been on the look out for such info.
You have noted very interesting details! ps decent website . “Become addicted to constant and never-ending self improvement.” by Anthony D’Angelo.
Merely wanna comment on few general things, The website pattern is perfect, the written content is rattling excellent. “Taxation WITH representation ain’t so hot either.” by Gerald Barzan.
Some truly nice and useful info on this site, too I think the design and style has got excellent features.
I like what you guys are up too. Such clever work and reporting! Keep up the excellent works guys I have incorporated you guys to my blogroll. I think it will improve the value of my web site 🙂
You are my inspiration, I have few blogs and rarely run out from brand :). “Fiat justitia et pereat mundus.Let justice be done, though the world perish.” by Ferdinand I.
You are my inspiration, I own few blogs and occasionally run out from post :). “He who controls the past commands the future. He who commands the future conquers the past.” by George Orwell.
Hello my friend! I want to say that this article is amazing, nice written and include approximately all vital infos. I?¦d like to look extra posts like this .
I love your blog.. very nice colors & theme. Did you create this website yourself? Plz reply back as I’m looking to create my own blog and would like to know wheere u got this from. thanks
In this grand pattern of things you get an A for effort and hard work. Exactly where you actually lost everybody was first on all the particulars. As as the maxim goes, details make or break the argument.. And that could not be much more accurate here. Having said that, allow me tell you precisely what did work. Your authoring is definitely extremely powerful and this is most likely why I am making the effort in order to comment. I do not really make it a regular habit of doing that. 2nd, even though I can easily see a leaps in reason you come up with, I am not necessarily convinced of how you appear to unite the points which inturn help to make the actual conclusion. For the moment I shall subscribe to your position but hope in the near future you actually connect the facts much better.
Howdy very cool web site!! Man .. Beautiful .. Wonderful .. I will bookmark your blog and take the feeds also…I am happy to seek out a lot of helpful info right here within the put up, we’d like develop extra strategies on this regard, thank you for sharing. . . . . .
very good publish, i actually love this website, carry on it
You could certainly see your expertise in the work you write. The world hopes for even more passionate writers like you who aren’t afraid to say how they believe. Always follow your heart.
Great post. I was checking continuously this blog and I am impressed! Extremely helpful info specially the last part 🙂 I care for such info a lot. I was looking for this certain information for a very long time. Thank you and best of luck.
I used to be recommended this web site by means of my cousin. I am no longer positive whether or not this put up is written through him as no one else realize such targeted approximately my trouble. You’re incredible! Thanks!
Hi there! This post couldn’t be written any better! Reading through this post reminds me of my previous room mate! He always kept talking about this. I will forward this article to him. Pretty sure he will have a good read. Thank you for sharing!
fantastic publish, very informative. I wonder why the opposite specialists of this sector do not understand this. You must continue your writing. I am sure, you have a great readers’ base already!
I like your writing style truly loving this web site.
I’m really enjoying the theme/design of your site. Do you ever run into any internet browser compatibility problems? A few of my blog readers have complained about my website not working correctly in Explorer but looks great in Chrome. Do you have any tips to help fix this problem?
It is really a great and helpful piece of information. I am glad that you shared this helpful information with us. Please keep us up to date like this. Thanks for sharing.
I discovered your blog site on google and test a number of of your early posts. Continue to keep up the superb operate. I simply further up your RSS feed to my MSN News Reader. In search of ahead to studying more from you later on!…
Thanks a lot for sharing this with all of us you actually know what you’re talking about! Bookmarked. Please also visit my site =). We could have a link exchange contract between us!
Very interesting information!Perfect just what I was looking for! “It’s not the having, its the getting.” by Elizabeth Taylor.
Hey very nice blog!! Guy .. Beautiful .. Wonderful .. I will bookmark your site and take the feeds additionallyKI am glad to seek out numerous useful info here within the put up, we want work out more techniques in this regard, thanks for sharing. . . . . .
Some genuinely howling work on behalf of the owner of this website , utterly outstanding content material.
I carry on listening to the reports speak about getting boundless online grant applications so I have been looking around for the best site to get one. Could you advise me please, where could i acquire some?
After all, what a great site and informative posts, I will upload inbound link – bookmark this web site? Regards, Reader.
Yeah bookmaking this wasn’t a risky decision outstanding post! .
Greetings! Very helpful advice on this article! It is the little changes that make the biggest changes. Thanks a lot for sharing!
I was studying some of your articles on this site and I think this web site is rattling instructive! Keep on posting.
I have been absent for some time, but now I remember why I used to love this website. Thank you, I will try and check back more frequently. How frequently you update your site?
I keep listening to the news bulletin speak about receiving free online grant applications so I have been looking around for the top site to get one. Could you advise me please, where could i get some?
Really nice style and fantastic content, nothing at all else we need : D.
Hiya, I am really glad I’ve found this information. Nowadays bloggers publish only about gossips and net and this is actually frustrating. A good website with exciting content, this is what I need. Thank you for keeping this web-site, I will be visiting it. Do you do newsletters? Can’t find it.
Some really nice and useful info on this web site, likewise I believe the layout has got wonderful features.
Great ?V I should definitely pronounce, impressed with your site. I had no trouble navigating through all tabs as well as related info ended up being truly easy to do to access. I recently found what I hoped for before you know it at all. Quite unusual. Is likely to appreciate it for those who add forums or something, web site theme . a tones way for your client to communicate. Nice task..
I think other site proprietors should take this site as an model, very clean and great user genial style and design, let alone the content. You are an expert in this topic!
Great site you have here but I was wondering if you knew of any discussion boards that cover the same topics talked about in this article? I’d really like to be a part of community where I can get feedback from other knowledgeable people that share the same interest. If you have any suggestions, please let me know. Cheers!
What i don’t understood is actually how you are not actually much more well-liked than you may be right now. You’re so intelligent. You realize thus significantly relating to this subject, made me personally consider it from numerous varied angles. Its like women and men aren’t fascinated unless it is one thing to accomplish with Lady gaga! Your own stuffs excellent. Always maintain it up!
Hey, you used to write magnificent, but the last few posts have been kinda boring… I miss your tremendous writings. Past several posts are just a bit out of track! come on!
WONDERFUL Post.thanks for share..more wait .. …
Thanks a bunch for sharing this with all of us you really know what you’re talking about! Bookmarked. Please also visit my website =). We could have a link exchange arrangement between us!
I am continually searching online for ideas that can help me. Thanks!
Excellent post. I used to be checking continuously this blog and I’m inspired! Very useful info specially the closing section 🙂 I handle such info a lot. I was seeking this particular information for a very long time. Thanks and best of luck.
Hello, you used to write fantastic, but the last few posts have been kinda boringK I miss your tremendous writings. Past several posts are just a little bit out of track! come on!
You actually make it seem so easy with your presentation but I find this matter to be actually something which I think I would never understand. It seems too complicated and extremely broad for me. I’m looking forward for your next post, I will try to get the hang of it!
I have to express my affection for your kindness giving support to individuals who really need guidance on this one theme. Your special dedication to passing the solution throughout has been unbelievably advantageous and has really helped some individuals just like me to achieve their desired goals. Your own useful advice denotes a whole lot to me and further more to my colleagues. Thank you; from everyone of us.
F*ckin¦ amazing things here. I am very satisfied to see your article. Thank you so much and i’m looking ahead to contact you. Will you please drop me a e-mail?
Do you mind if I quote a few of your posts as long as I provide credit and sources back to your blog? My blog site is in the exact same niche as yours and my users would really benefit from some of the information you provide here. Please let me know if this alright with you. Thanks!
Hello there, You have performed a fantastic job. I’ll certainly digg it and individually recommend to my friends. I’m confident they’ll be benefited from this website.
Hey, you used to write great, but the last several posts have been kinda boringK I miss your super writings. Past few posts are just a bit out of track! come on!
Admiring the persistence you put into your blog and detailed information you present. It’s good to come across a blog every once in a while that isn’t the same unwanted rehashed information. Excellent read! I’ve saved your site and I’m adding your RSS feeds to my Google account.
Thanks for your personal marvelous posting! I really enjoyed reading it, you may be a great author.I will remember to bookmark your blog and will often come back at some point. I want to encourage that you continue your great writing, have a nice morning!
of course like your web-site but you need to test the spelling on quite a few of your posts. Several of them are rife with spelling problems and I find it very bothersome to tell the truth however I’ll certainly come again again.
Thank you for the sensible critique. Me and my neighbor were just preparing to do a little research about this. We got a grab a book from our area library but I think I learned more clear from this post. I’m very glad to see such magnificent information being shared freely out there.
Thanks for your whole effort on this website. My mother takes pleasure in setting aside time for research and it is simple to grasp why. All of us notice all regarding the powerful tactic you make powerful solutions through this web blog and even attract response from visitors on that idea plus our own simple princess is starting to learn a great deal. Take pleasure in the rest of the year. You are always performing a tremendous job.