Can you identify the distinctions between these two function expressions?

Question

Can you identify the distinctions between these two function expressions?

Could you please clarify something for me? Below is an example of a function statement:

function foo() {}

However, the following examples are all function expressions.

var foo = function() { } // or
var foo = function foo() { } // or 
var foo = new function() { }

My question is, what distinguishes between these two forms of a function expression?

var foo = function() { } // and
var foo = new function() { }

Is the second one also considered a constructor expression? If so, which "class" does it belong to (keeping in mind that JavaScript doesn't have traditional classes but rather templates, functions, or prototypes)?

Update

To those who have shared related questions, I want to express my gratitude. Learning this language has been quite overwhelming for me as a beginner, and while I find it fascinating, it can also be confusing at times. I hope to fully grasp the intricacies of this beautiful language eventually. Please continue suggesting other relevant resources if possible.

javascript

Answer 1

Answer №1

Here is an example:

const bar = function() { }

This code creates a new function and assigns it to the variable bar.

On the other hand, consider this:

const bar = new function() { }

In this case, a function is instantiated, called with a new object as its context, and the resulting object is assigned to the variable bar. The function itself is not retained unless it somehow manages to return itself.

This second scenario is quite uncommon in well-written code.

Answer 2

Here is an example:

const bar = function() { }

This code creates a new function and assigns it to the variable bar.

On the other hand, consider this:

const bar = new function() { }

In this case, a function is instantiated, called with a new object as its context, and the resulting object is assigned to the variable bar. The function itself is not retained unless it somehow manages to return itself.

This second scenario is quite uncommon in well-written code.

Answer 3

Answer №2

A Function Expression is a way to define a function within an expression, usually as part of assigning it to a variable. Functions created through Function Expressions can be either named or anonymous.

Here are examples of function expressions that define a function and assign it to the variable bar:

var bar = function() { }

var bar = function bar() { }

Using the new keyword does not create a new function, but rather creates an object that is then assigned to the variable bar; the newly created function is also invoked immediately.

var bar = new function() { }

Answer 4

A Function Expression is a way to define a function within an expression, usually as part of assigning it to a variable. Functions created through Function Expressions can be either named or anonymous.

Here are examples of function expressions that define a function and assign it to the variable bar:

var bar = function() { }

var bar = function bar() { }

Using the new keyword does not create a new function, but rather creates an object that is then assigned to the variable bar; the newly created function is also invoked immediately.

var bar = new function() { }

Can you identify the distinctions between these two function expressions?

Answer №1

Answer №2

Similar questions

Is there a way to access the history of Vue routers?

Tips for transferring a dynamic ID from AJAX data to a modal

Google Maps is experiencing difficulties with loading

Issue with exporting variable from Node.js module was encountered

Tips on combining $scope object values within AngularJS

Closing the Bootstrap navbar collapse by clicking anywhere outside of the menu area

Waiting for the HTTP response in NodeJS before sending the next request

Accessing the variable's value within a separate if statement within the function

Dividing a single AJAX request containing 5000 rows into separate AJAX calls each returning 100 rows

Trick to trigger a redraw in reactJS?

Experiencing difficulties with extracting information from mySQL for my web development assignment

Leveraging the useContext and useReducer hooks within NextJS, while encountering the scenario of reading null

Trigger the opening of a popup modal using a JavaScript function

PHP class variable not updating properly when using XMLHttpRequest

Activate browser scrollbar functionality

Once map layers have been loaded initially, they will not render again

Animating object properties instead of static values

Error with shader in webgl/three.js

How can I dynamically append content to the DOM when a user clicks?

What is the process for uploading an image encoded in base64 through .ajax?