what is optional chaining used for in javascript - Brave Search

How can I use optional chaining with arrays and functions?

stackoverflow.com › questions › 59623674 › how-can-i-use-optional-chaining-with-arrays-and-functions

You need to put a . after the ? to use optional chaining:

myArray.filter(x => x.testKey === myTestKey)?.[0]

Playground link

Using just the ? alone makes the compiler think you're trying to use the conditional operator (and then it throws an error since it doesn't see a : later)

Optional chaining isn't just a TypeScript thing - it is a finished proposal in plain JavaScript too.

It can be used with bracket notation like above, but it can also be used with dot notation property access:

const obj = {
  prop2: {
    nested2: 'val2'
  }
};

console.log(
  obj.prop1?.nested1,
  obj.prop2?.nested2
);

And with function calls:

const obj = {
  fn2: () => console.log('fn2 running')
};

obj.fn1?.();
obj.fn2?.();

Answer from CertainPerformance on Stack Overflow

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Operators › Optional_chaining

Optional chaining (?.) - JavaScript | MDN

The optional chaining (?.) operator accesses an object's property or calls a function. If the object accessed or function called using this operator is undefined or null, the expression short circuits and evaluates to undefined instead of throwing an error.

JavaScript.info

javascript.info › tutorial › the javascript language › objects: the basics

Optional chaining '?.'

The optional chaining works only for declared variables. As it was said before, the ?. immediately stops (“short-circuits”) the evaluation if the left part doesn’t exist. So, if there are any further function calls or operations to the ...

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freecodecamp.org › news › optional-chaining-javascript

Optional Chaining in JavaScript – Explained with Examples

February 13, 2024 - Here, the optional chaining operator is used to access the name property of each user's profile. If any intermediate property in the chain is null or undefined, the expression short-circuits, and "Unknown" is returned as the default value.

stackoverflow.com › questions › 59623674 › how-can-i-use-optional-chaining-with-arrays-and-functions

javascript - How can I use optional chaining with arrays and functions? - Stack Overflow

You need to put a . after the ? to use optional chaining:

myArray.filter(x => x.testKey === myTestKey)?.[0]

Playground link

Using just the ? alone makes the compiler think you're trying to use the conditional operator (and then it throws an error since it doesn't see a : later)

Optional chaining isn't just a TypeScript thing - it is a finished proposal in plain JavaScript too.

It can be used with bracket notation like above, but it can also be used with dot notation property access:

const obj = {
  prop2: {
    nested2: 'val2'
  }
};

console.log(
  obj.prop1?.nested1,
  obj.prop2?.nested2
);

And with function calls:

const obj = {
  fn2: () => console.log('fn2 running')
};

obj.fn1?.();
obj.fn2?.();

Just found it after a little searching on the what's new page on official documentation

The right way to do it with array is to add . after ?

so it'll be like

myArray.filter(x => x.testKey === myTestKey)?.[0] // in case of object
x?.() // in case of function

I'll like to throw some more light on what exactly happens with my above question case.

myArray.filter(x => x.testKey === myTestKey)?[0]

Transpiles to

const result = myArray.filter(x => x.testKey === myTestKey) ? [0] : ;

Due to which it throws the error since there's something missing after : and you probably don't want your code to be transpilled to this.

Thanks to Certain Performance's answer I learned new things about typescript especially the tool https://www.typescriptlang.org/play/index.html .

geeksforgeeks.org › javascript › javascript-optional-chaining

JavaScript Optional Chaining - GeeksforGeeks

... The Optional Chaining Operator allows a developer to handle many of those cases without repeating themselves by assigning intermediate results in temporary variables: ... Note: If this code gives any error try to run it on online JavaScript ...

Published June 22, 2020

reddit.com › r/javascript › [askjs] over-using optional chaining. is this pattern common?

r/javascript on Reddit: [AskJS] Over-using optional chaining. Is this pattern common?

January 18, 2021 -

Hi everyone!

I love optional chaining, i really do, but there are some cases where using this syntax damages the readability of the code. One of those cases is the following

function optionalFunction(){     
    console.log("works"); 
}  
// optionalFunction = undefined;  

optionalFunction?.();

While i understand this approach, i find it optionalFunction?.() harder to read as opposed to this

function optionalFunction(){     
    console.log("works"); 
}  
// optionalFunction = undefined;  

if(optionalFunction != undefined){     
    optionalFunction(); 
}

I think i'd rather have a more readable and stronger check than ES6 magic when checking if an optional function is defined.

I believe that optional chaining fixes the problem of checking if a property of an object exists, and if exists, then get the value or keep going deeper in the object structure. But this syntax just looks weird for calling functions, it looks a lot like those "one line cleverness" code that sometimes people encounter.

What are your thoughts about this?

Optional chaining is great. I find it however quite frustrating that TC39 included the "optional call" syntax that you're illustrating. THAT is a terrible feature that should be avoided, IMO. Besides it looking weird (like a typo), one reason I dislike it so much is that it seems (to the reader) like it's checking if the function can be called, and only calling it if safe to do so. But that's not what it's doing. It's only checking if the callee is not-nullish. var isThisAFunction1 = null; var isThisAFunction2 = "oops"; // later isThisAFunction1?.(); // safely a no-op isThisAFunction2?.(); // Exception!

I haven't really started using optional chaining yet, but the idiom I mostly encounter for optional callbacks etc. is onEnd && onEnd() I would personally only use optional chaining for "deeply" nested properties. const city = user.?address?.city || defaultCity

dev.to › codeofrelevancy › javascripts-optional-chaining-operator-3pfn

JavaScript's Optional Chaining (?.) Operator - DEV Community

March 28, 2023 - ... The Optional Chaining (?.) operator is a powerful and elegant feature in JavaScript that can simplify our code and prevent runtime errors. By allowing us to safely access properties and call methods without having to check for undefined ...

forum.freecodecamp.org › javascript

What Is the Optional Chaining Operator, and How Does It Work? - JavaScript - The freeCodeCamp Forum

April 8, 2025 - TLDR: Optional Chaining Operator is for objects, not properties? https://www.w3schools.com/jS/js_2020.asp " The Optional Chaining Operator returns undefined if an object is undefined or null (instead of throwing an error)."

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v8.dev › features › optional-chaining

Optional chaining · V8

// Still checks for errors and is much more readable. const nameLength = db?.user?.name?.length; What happens when db, user, or name is undefined or null? With the optional chaining operator, JavaScript initializes nameLength to undefined instead of throwing an error.

freecodecamp.org › news › javascript-optional-chaining

How to Use Optional Chaining in JavaScript

February 7, 2022 - Optional chaining is a safe and concise way to perform access checks for nested object properties. The optional chaining operator ?. takes the reference to its left and checks if it is undefined or null.

codecademy.com › docs › javascript › optional chaining

JavaScript | Optional Chaining | Codecademy

August 7, 2025 - The optional chaining operator allows safe access to nested object properties or methods without having to explicitly check if intermediate properties exist.

daily.dev › home › blog › webdev › optional chaining in javascript - what is it and how to use it?

Optional Chaining In JavaScript - What Is It And How To Use It?

November 1, 2021 - The optional chaining feature is similar to the `.` chaining operator. The only difference is that it returns the value of undefined if the reference is `null` or `undefined`. That is if the object property does not exist.

medium.com › @mfarazali › optional-chaining-operator-in-javascript-5866c8cecc68

Optional Chaining Operator (?.) in Javascript | by Muhammad Faraz Ali | Medium

March 14, 2024 - Optional chaining operator (?.) which is useful to access a property of an object which may be null or undefined. Combining them, you can safely access a property of an object which may be nullish (null or undefined) and provide a default value ...

tutorialspoint.com › javascript › javascript_optional_chaining.htm

JavaScript - Optional Chaining

It is placed before the property or method that you want to access. If the property or method does not exist, the expression will evaluate to undefined instead of throwing an error. Let's understand the need for optional chaining in JavaScript via the non-existing property problem.

medium.com › nerd-for-tech › using-the-optional-chaining-operator-in-javascript-aa56d19acef7

Using the optional chaining operator in JavaScript | by saransh kataria | Nerd For Tech | Medium

March 23, 2021 - It checks nested properties for us without having to explicitly search down the ladder. All you have to do is use the “?” operator after the property that you want to check for nullish values.

fjolt.com › article › javascript-optional-chaining

How does Optional Chaining work in Javascript?

It’s used when properties are optional on an object, so that instead of returning an error, we still get a result from Javascript. Let’s look at how it works. Anyone who has used Javascript for any length of time may have run into a pretty ...

Dmitri Pavlutin

dmitripavlutin.com › javascript-optional-chaining

How to Use JavaScript Optional Chaining

Optional chaining is also available in TypeScript, starting from version 3.7. Let's see how optional chaining makes your code simpler when accessing potentially null or undefined properties.

freecodecamp.org › news › javascript-optional-chaining-explained

JavaScript Optional Chaining `?.` Explained - How it Works and When to Use it

August 25, 2020 - Optional chaining, represented by ?. in JavaScript, is a new feature introduced in ES2020. Optional chaining changes the way properties are accessed from deeply nested objects. It fixes the problem of having to do multiple...

medium.com › @ajithr116 › optional-chaining-in-javascript-21348de56ac0

optional chaining in javascript. Optional chaining in JavaScript is a… | by Ajith R | Medium

August 22, 2024 - It allows you to write code that attempts to access a property of an object, but if any level in the chain is `null` or `undefined`, it will return `undefined` instead of throwing an error.

udn.realityripple.com › docs › Web › JavaScript › Reference › Operators › Optional_chaining

Optional chaining (?.) - JavaScript

The optional chaining operator (?.) permits reading the value of a property located deep within a chain of connected objects without having to expressly validate that each reference in the chain is valid. The ?. operator functions similarly to the . chaining operator, except that instead of ...