Using `this` within an object declaration

Question

Using `this` within an object declaration

I am encountering an issue with the following code snippet:

const myObj = {
        reply(text: string, options?: Bot.SendMessageOptions)
        {
            return bot.sendMessage(msg.chat.id, text, { reply_to_message_id: msg.message_id, ...options });
        },
        replyMd(text: string, options?: Bot.SendMessageOptions)
        {
            return this.reply(text, { parse_mode: "Markdown" });
        }
};

Despite my efforts to call replyMd, I am facing a problem where this remains undefined. How can I resolve this issue?

javascript typescript

Answer 1

Answer №1

Let's look at this scenario:

const foo = {
  bar() {
    console.log(this)
  }
}

When you invoke foo.bar(), it will output

Object {bar: function bar()}

However,

const {bar} = foo
bar()

will output undefined

For further explanation, refer to this informative article on MDN.

Within a function, the context of this varies depending on how the function is invoked. [...] When a function is called as an object's method, its this refers to that specific object.

Answer 2

Let's look at this scenario:

const foo = {
  bar() {
    console.log(this)
  }
}

When you invoke foo.bar(), it will output

Object {bar: function bar()}

However,

const {bar} = foo
bar()

will output undefined

For further explanation, refer to this informative article on MDN.

Within a function, the context of this varies depending on how the function is invoked. [...] When a function is called as an object's method, its this refers to that specific object.

Using `this` within an object declaration

Answer №1

Similar questions

Angular2 - adding the authentication token to request headers

Preventing the reoccurrence of function events

Is there a way to focus on a specific iteration of the ngFor loop in Angular 9 using jQuery?

Chrome's keyup event restricts the use of arrow keys in text fields

Exploring Appsetting Configuration in AppModule of Angular 8

Tips for producing/reserving cropped images from a photo? (includes converting images to base64 format)

Utilizing a dictionary for comparing with an API response in order to generate an array of unique objects by eliminating duplicates

The operation is unable to be executed in an external document

detect and handle errors when deploying the Node.js function

Step-by-Step Guide for Uploading an Entire Folder and Its Contents

Reactjs encountering issues with CSS loading correctly

How can a React app be developed offline?

Step-by-step guide on duplicating a div a set number of times

Gain access to PowerBI reports effortlessly without the need to input any credentials

What are the differences between Sitecore Analytics and Adobe Analytics? How do they each utilize JavaScript

I am facing an issue with the Angular2 Modal Form where it only displays the data but does

Passing parameters to a new page in AngularJS using ng-click event

Encountering an issue with the message: "Property 'ref' is not available on the type 'IntrinsicAttributes'."

How can I utilize a filter or pipe to populate product categories onto screens within Ionic 2?

Is the toString() method explicitly invoked by Number() if the value is not of type number or string? (such as a function)