What purpose does the question mark (?) serve after a class name when invoking class methods in TypeScript?

One interesting element within my TypeScript code snippet is the presence of the statement row?.delete();.

I'm curious about the significance of the question mark in this context.

What would be the outcome if 'row' happened to be null?

Appreciate any insights!

Answer №1

Optional chaining, represented by the row?.delete() syntax, is an operator that first verifies if the row is defined before attempting to access the delete method.

If the row is null, using row?.delete() will simply return undefined. Without the optional chaining operator, trying to call row.delete() on a null row would result in a

Uncaught Type Error: Cannot read property 'row' of undefined
.

For further information and examples, you can visit https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html

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

Exploring the synergies between Angular 5 and atmosphere.js

I've been trying to incorporate atmosphere.js into my angular 5 project. So far, I've followed these steps: npm install --save @types/atmosphere.js npm install --save atmosphere.js In addition, I have set up a service as shown below: import { ...

What steps do I need to take to link my form with Ajax and successfully submit it?

Here is my HTML code: {% extends 'base.html' %} {% block content %} <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Create a Recipe ...

Is it achievable to have a Dynamic Angular Output?

With multiple parent components needing a common child component that can dynamically and automatically adapt to each case, I am faced with the challenge of generating buttons using a forEach loop with data provided by the parent component (such as name, C ...

Include a predetermined parameter for the upcoming callback

Currently, I am working on loading files asynchronously by utilizing d3's queue, defer, and await features. The issue arises when I attempt to execute this process in a loop, where for each iteration, I aim to store the retrieved data in a dictionary: ...

The method of inserting a JSON dates object to deactivate specific days

I am currently utilizing a date picker component that can be found at the following link: While attempting to use the disabledDays section below, I have encountered an issue where I am unable to apply all three options. The blockedDatesData option works o ...

What is the best method for encrypting a file using node.js?

I am in the process of finding a way to encrypt various types of files like txt, mp3, or any other file in node.js while utilizing socket.io. My goal is to develop an application that can securely send files to another client, so I wish to encrypt the file ...

Converting a JavaScript string containing an `import` statement into a browser-compatible function

Can my vue application transform the given string into a callable function? const test = 'import { pi } from "MathPie"; function test() { console.log(pi); } export default test;' The desired output format is: import { pi } from "M ...

How to retrieve a refined selection of items

In my scenario, there are two important objects - dropdownOptions and totalItem https://i.sstatic.net/VreXd.png The requirement is as follows: If 12 < totalItems < 24, then display "Show 12, Show 24" If 24 < totalItems < 36, only show "Show ...

Enhance Vaadin 14: Automatically adjust TextArea size when window is resized

Using Vaadin 14.1.19 in a project called "My Starter Project," I attempted to create a TextArea that supports multiple lines. Initially, everything seemed fine, but upon resizing the TextArea, it failed to adjust the number of visible lines. Here is the co ...

Exploring the capabilities of Socket.IO in Node.js for establishing a connection with an external server

Background: My localhost (referred to as Server A) hosts a node.js server, while an external server running node.js can be found at (known as Server B). Although I lack control or access over Server B, which serves as a dashboard site for an IoT device in ...

How can I display different data values on each individual circle counter, rather than all circles showing the same data?

Hey there! I'm trying to get my circular counters to display the counter value that I specify in their class and data-percent. However, currently all four counters are only showing the data from the first counter, even though I've set different d ...

Guide on accessing and setting values in GridView Cell using JavaScript

Within my layout, I have two labels named FixedTotal and TotalPercent, as well as a single row GridView with columns labeled ReferenceID, Percentage, and Amount. ReferenceID Percentage Amount -------------- ------------- --- ...

Implementing timeAgo with jQuery (or a similar tool) to display the elapsed time since a user (client) accesses or updates a webpage

https://i.sstatic.net/Y7bzO.png Currently, the timer displayed always shows the actual time instead of phrases like "about a minute ago" or "5 minutes ago". I have tried different solutions without success. //timeago by jQuery (function timeAgo(selector) ...

Experiencing challenges with showcasing numerical values in the grid cells

My latest project involves creating an interactive sudoku solver. I've successfully created a grid made up of various elements to resemble an empty sudoku grid. However, my challenge lies in getting the numbers to display within the grid cells. Click ...

Learn the process of importing data types from the Firebase Admin Node.js SDK

I am currently facing a challenge with importing the DecodedIDToken type from the https://firebase.google.com/docs/reference/admin/node/firebase-admin.auth.decodedidtoken. I need this type to be able to assign it to the value in the .then() callback when v ...

Switch all occurrences of https URLs with <a> using the stencil technology

I am encountering an issue with replacing the answer retrieved from an API and formatting it correctly answerFromAPI = "textword textword textword textword textword.\n\nFeel free to ask me questions from this site:\nhttps://google.com &bso ...

In order to properly execute the JavaScript code, it is essential to create a highly customized HTML layout from the ER

I am currently utilizing this resource to create a gallery of images on my Rails page. Here is the HTML code required to display the images: <a href="assets/gallery/ave.jpg" title="Ave" data-gallery> <img src="assets/gallery/ave_tb.jpg" alt="Av ...

executing a function from one controller within another controller

I am currently working on a modal where, upon clicking the delete button, I need to execute the delete() function from controller A within controller B https://i.sstatic.net/HJhGT.png As part of my refactoring process, I am updating the Todo App example ...

I am experiencing an issue with my service provider when it comes to displaying multiple navigator stacks

Currently, I am developing a provider to manage the user's state across different views. The primary function of this provider is to display either one stack navigator or another based on whether a certain variable is filled or empty. This setup allow ...

The specified property 'length' is not found on type OkPacket within the mysql2 module

In my code example below, I am simply showcasing a specific scenario: this.getCode = (code: string): Promise<codeObject | false> => { return new Promise((resolve, reject) => { pool.query('SELECT * FROM ?? WHERE code = ...