JavaScript Vanilla | Object that can be invoked and also has a property

Question

JavaScript Vanilla | Object that can be invoked and also has a property

In an assignment, I was given the following task:

fun4(): must return an object that can be called as a function. This object should also have a 'k' property with a null value (so fun4()() should perform some action).

The first part of the question is clear and easy to understand. However, the second part is where I am struggling. How can I create a JavaScript object that can be both invoked and accessed statically?

To put it simply: Is it possible to create an object that behaves like this?

> let o = CustomObject;
> o.k
< null
> o()
< //Some value returned here from the function

Any help or guidance on this would be greatly appreciated!

javascript json

Answer 1

Answer №1

This seems quite clear from my perspective...

const SpecialObject = function(){ return "hello"; }
SpecialObject.j = null;

These steps meet your Certification requirements

Answer 2

This seems quite clear from my perspective...

const SpecialObject = function(){ return "hello"; }
SpecialObject.j = null;

These steps meet your Certification requirements

Answer 3

Answer №2

Vanilla JavaScript offers a solution for what you seek:

var fun5 = function () {
    let value = function () { console.log("hi there"); };
    value.key = null;

    return value;
}


fun5()   // retrieves the function
fun5()() // prints 'hi there'
fun5().key // returns null

In response to one of your previous comments, it is essential to be mindful of using let versus var. In this scenario, either can be utilized without affecting the outcome (as value gets released for garbage collection when the function concludes). However, if you execute this in the console (outside a defined scope), variables created with let will be reset after each execution -- meaning every time you hit enter. To illustrate the difference, consider the following:

var example = function () {
    let y = 1;
    let y = 1;  // this will result in an immediate syntax error during script parsing;
}

Conversely:

> let y = 1;
< undefined
> let y = 1; // When run in the console, no error/exception occurs
             // because the scope is cleared post the preceding line's
             // execution and return
< undefined

Answer 4

Vanilla JavaScript offers a solution for what you seek:

var fun5 = function () {
    let value = function () { console.log("hi there"); };
    value.key = null;

    return value;
}


fun5()   // retrieves the function
fun5()() // prints 'hi there'
fun5().key // returns null

In response to one of your previous comments, it is essential to be mindful of using let versus var. In this scenario, either can be utilized without affecting the outcome (as value gets released for garbage collection when the function concludes). However, if you execute this in the console (outside a defined scope), variables created with let will be reset after each execution -- meaning every time you hit enter. To illustrate the difference, consider the following:

var example = function () {
    let y = 1;
    let y = 1;  // this will result in an immediate syntax error during script parsing;
}

Conversely:

> let y = 1;
< undefined
> let y = 1; // When run in the console, no error/exception occurs
             // because the scope is cleared post the preceding line's
             // execution and return
< undefined

Answer 5

Answer №3

Below, you will find the 'k' attribute.

https://i.sstatic.net/ww9zZ.png

Answer 6

Below, you will find the 'k' attribute.

https://i.sstatic.net/ww9zZ.png

JavaScript Vanilla | Object that can be invoked and also has a property

Answer №1

Answer №2

Answer №3

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