What is the target of the `__proto__` attribute in a constructor function?

I'm taking the time to dive deeper into prototypal inheritance. I know that an instance's __proto__ property points to the constructor function's prototype object, but where does the constructor function's __proto__ property point to?

I initially thought that since the constructor function is also an instance of Function, it would point to the Function constructor's prototype object. However, it turns out to be an empty function.

var Example = function(){
   this.attribute = 'example';
}

var exampleInstance = new Example();

exampleInstance.__proto__ === Example.prototype // true
Example.__proto__ // function() {}

[Edit] Ovidiu Dolha has now validated my understanding, so perhaps this will be beneficial for someone else.

Answer №1

Instance.exampleProto will be identical to Prototype.function, just as sample.__proto__ is equivalent to Instance.prototype

This occurs because Instance is a type of Function.

Eventually, everything will trace back to Object.prototype, which serves as the core in terms of prototypal inheritance.

It's worth noting that it's recommended to avoid using __proto__ whenever possible, as it is now considered deprecated. Instead, opt for Object.getPrototypeOf()

Answer №2

There is a prototype chain that extends all the way to the "Object" as the ultimate root.

According to the ECMAScript 5.1 specification, it is defined as follows:

Section 15.3.4 Properties of the Function Prototype Object:

The [[Prototype]] internal property value of the Function prototype object is the default built-in Object prototype object.

Additionally, in Section 15.2.4 Properties of the Object Prototype Object:

The [[Prototype]] internal property value of the Object prototype object is set to null.

You can test this in your console.

console.log(exampleInstance);

Example
attribute: "example"
__proto__: Object
constructor: ()
__proto__: Object
__defineGetter__: __defineGetter__()
__defineSetter__: __defineSetter__()
__lookupGetter__: __lookupGetter__()
__lookupSetter__: __lookupSetter__()
constructor: Object()
hasOwnProperty: hasOwnProperty()
isPrototypeOf: isPrototypeOf()
propertyIsEnumerable: propertyIsEnumerable()
toLocaleString: toLocaleString()
toString: toString()
valueOf: valueOf()
get __proto__: __proto__()
set __proto__: __proto__()

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Knockout.JS encounters difficulty retrieving the value attribute in a select tag when the data is sourced from the server

After making an ajax request and binding the dropdown list, I noticed that the select tag was not reading the value attribute. However, when I bind the drop down list in the view model, it does recognize the value. For example: It works if I bind the mode ...

Using `this` in a Jquery get() call to reference a callback function

Utilizing the this keyword in the callbacks of $.get() is my current challenge. The outline of my code looks like this: var myObject = { get: function() { $.get(server,data,function(data,status) { this.callback(); }); }, callback: func ...

Enhancing the camera functionality of the HTML <input> tag for iPhone and Android devices

I am currently working on a mobile web application that requires access to the device's camera. I am aware that this can be achieved using the following code: <input type="file" accept="image/*" capture="camera" /> The code snippet above suc ...

What is the best way to extract the essential data from the returned value without any unnecessary additions?

Looking for a way to extract specific data from an api response in the format of x[[seconds:cost[[x? I am using php and javascript. How can I separate out the seconds and cost values only? For example, if the response looks like this: x[[16413:2.60[[x I ...

Guide on updating individual rows in Google App Script using data from a different sheet

I am trying to create a script that will pull a value from column[3] in the ZONE sheet to the active sheet, specifically in column 56 of the job sheet when the zonelist value matches the zone value in different sheets. The script should check the range fro ...

"Exploring the various configurations for session handling in NodeJs

I am trying to implement a login system using the express-session module. I'm unsure if I have set everything up correctly, especially when it comes to the secret option. Currently, my initialization code for express-session looks like this: app.use( ...

Is there a way to ensure that the code only runs if the promise has been successfully fulfilled

In my NodeJS project, I am leveraging promises to ensure that the server stops running if certain functions do not meet the required conditions. Currently, the server halts as intended, but I also want to include a console log message when the promises are ...

How to assign a preset value to a text area in AngularJS

While working with PHP and AngularJS, I have a requirement to specify the default value for a textarea. I prefer not to utilize ng-init="textarea = ''" as the data to populate is extensive. Similarly, I want to avoid using AJAX to prevent additi ...

Merging double borders in a div using CSS is essential for creating

Upon examining this sample, it's evident that the borders do not blend together. css: div{ float:left; background-color:moccasin; width:100px; height:100px; border:1px solid tomato; } The number of divs is arbitrary, and only on ...

Obtaining the most recently inserted ID in Node.js can be achieved by using

Currently in my Nodejs project, I am using the expressjs framework. I am facing an issue where I am trying to retrieve the "last inserted id", but it is showing as "undefined" in the console. How can I successfully get the last inserted id? Below is the ...

"Encountering a RangeError with Node.js Sequelize while working with

I need some assistance with using Sequelize in my Node.js application paired with MySQL. When I try to execute the command npx sequelize db:create, I encounter an error that I do not know how to resolve. Any guidance on this matter would be greatly appreci ...

Obtaining a value from an input field in Vue.js

Just starting out with Vue and could use a hand extracting a value from an input field: Here's what I have in my form: <input type="hidden" id="groupId" value="1"> If I were using jQuery, I would do the following: ...

Tips on how to patiently wait until the database connection is established and all queries are successfully executed for every database specified in an array

A file containing JSON data with database details needs to execute a series of queries for each database connection. The map function is currently waiting for the database connection. Below is the start function function start() { console.log('func ...

Obtaining JSON data in a separate JavaScript file using PHP

I have an HTML file with the following content: // target.html <html xmlns="http://www.w3.org/1999/xhtml"> ... <script src="../../Common/js/jquery-ui-1.10.3.js"></script> <script src="../../Common/js/select.js" type="text/javascript"& ...

Encountering a Typescript TypeError in es2022 that is not present in es2021

I'm attempting to switch the target property in the tsconfig.json file from es2015 to es2022, but I am encountering an error while running tests that seem to only use tsc without babel: Chrome Headless 110.0.5481.177 (Mac OS 10.15.7) TypeError: Can ...

Adding a dynamic form to each row in a table: A step-by-step guide

Hey there! I'm facing a challenge with dynamically generated rows in a form. I want to send only the inputs from the selected row when a checkbox is clicked. Can you help me figure this out? I tried using let rowForm = $(event.currentTarget).closest( ...

refresh polymer components or make an ajax request within a custom element

I've been spending days on this issue with no success! My application relies on cookies for session handling and includes multiple custom elements imported in the header. Some of these elements need to access information from the 'cookie session& ...

Utilize HTTPS and HTTP with Express framework in node.js

Currently, I am utilizing the express (3.0) framework on node.js to handle routing in my application. While most of the application makes use of the http protocol, there is a specific route that I intend to serve exclusively via https. This particular par ...

How can I effectively capture a change in the hour using Node.js?

Do you know of a more efficient way to monitor datetime changes instead of checking every 10 minutes, potentially firing nearly 10 minutes late? Any alternative solutions that I may have overlooked for this issue? ...

Enabling the submit button only when text is entered in the text fields using jQuery

I have a script that automatically submits a form when two textfields are filled using variables from local storage. The script checks if the variables for email and password are not null before submitting. if (localEmail != null && localPwd != null) { ...