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What is JavaScript's Anonymous and Arrow function?

Suraj Vishwakarma on July 18, 2022

Introduction William Shakespeare once said that “What’s in Name?” but as a developer, we can disagree. We have to name variables, classe...
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Jon Randy 🎖️ • • Edited

A lot of confusion and incorrect information in this article. Many of your 'anonymous' functions are not anonymous functions at all

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Suraj Vishwakarma •

If you read the article, it's for storing the function in a variable.

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Jon Randy 🎖️ • • Edited

Named function can’t be invoked immediately after declaration

This is not correct - you can declare a named function without a function statement, and immediately invoke it:

// this is a named function in a function expression
console.log( (function test() { console.log('hello') }).name )  // 'test'

// it can be invoked immediately
(function test() { console.log('hello') })()  // 'hello'
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It is true that you cannot immediately invoke a named function created with a function statement, but not true that you cannot invoke a named function immediately after declaration.

Immediate invocation is possible because the preceding code is an expression whose value is a function - it has nothing to do with whether the function is anonymous or not. If you have defined a function using a function statement - then that statement is not an expression and therefore has no value that you can call.

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Suraj Vishwakarma •

Considering this, I like to thank you as I was not having the knowledge on this. I have updated the article as per your feedback.

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Jon Randy 🎖️ • • Edited

If you read the article, it's for storing the function in a variable.

Yes, but the very act of assignment makes those functions cease to be anonymous functions. They acquire the name of the variable/constant. This can be shown by checking the function's name:

const notAnonymous = function () { return 1 }
console.log(notAnonymous.name)  // 'notAnonymous'
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Contrast this with an actual anonymous function:

console.log( (function() { return 1 }).name )  // ''
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Suraj Vishwakarma •

After the initial declaration of the anonymous function, it can't be invoked later. For that, we have to store it inside a variable. That's I did above. This has led to having a name.

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Jon Randy 🎖️ • 
setTimeout(myFunction() {
     conole.log(“1 minute has passed”)  
}, 1000)
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There are a number of mistakes in this example. Firstly - it won't run because myFunction() should say just function or function myFunction(). Further, console is misspelled and the message will display after 1 second, not one minute.

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Suraj Vishwakarma •

Typo fixed.