After receiving a variable from a network call of type optional String,
const receivedData = data.receivedData
Is there a shortcut method to construct a String using this variable and provide a default value when it's null?
const finalString = "Received data from " + receivedData
TypeScript version 3.7 brought in new support for the proposed JavaScript "nullish coalescing operator" ??. The syntax of this operator is someName ?? defaultValue, and it returns someName unless it is null or undefined, in which case it returns defaultValue. This operator is designed for short-circuiting, meaning defaultValue is not evaluated if someName is non-nullish.
Prior to TypeScript 3.7, a ternary operator was commonly used for similar results:
someName != null ? someName : defaultValueAlternatively, if you are not focused on null and undefined specifically and are okay with returning the default for any falsy value of someName (like an empty string ""), you can utilize the logical "or" operator: someName || defaultValue, which also short-circuits.
Feel free to use any of these options as they should all be effective. Best of luck with your coding endeavors!
I find template literals to be quite useful. One interesting technique is to combine them with the ternary operator to provide a default value when the variable is null or undefined.
Here's an example you can experiment with:
const data = {};
const someString = `You got something from ${data.someName ? data.someName : 'your default value'}`;
console.log(someString);For more information, check out the following resources:
I hope this explanation proves beneficial to you!
In the TypeScript code snippet provided, the type for 'e' (used in the function for form submission) has been figured out. However, a question arises if this type declaration is correct. Additionally, in the catch block, the type "any" is used fo ...
When working with a product, it's important to keep in mind that it can be undefined or null; furthermore, the price within the product can also be undefined or null. For example: getClasses(key: number): string { let product = this.mo ...
My API has a limitation of 50 requests per minute for any endpoint. In the code snippet below, I filter objects called orders based on their URLs and store the ones that return data in successfulResponses within my app.component.ts. Promise.all( orders.ma ...
Can someone assist me with an issue I'm facing in Vue where it's not detecting my Single File Components? Error message: ERROR in ./src/App.vue (./node_modules/ts-loader!./node_modules/vue-loader/lib/selector.js?type=script&index=0!./src/Ap ...
In my code, I have defined an interface as follows: export interface OurHistory { ourHistory?: object; step1?:object; step2?:object; } Within the HistoryComponent class, I am doing the following: export class HistoryComponent implements OnInit, On ...
Initially, I have a page form with preset values and buttons for navigating to the next or previous items. Upon initialization in ngOnInit, an observable provides me with a list of 3 items as the starting value - sometimes it may even contain 4 items. Ho ...
I've encountered a strange issue when using prisma seed in my nextjs full-stack project that I can't seem to figure out. Normally, when running the app with `next dev`, everything works smoothly and the queries are executed without any problems. ...
I am encountering an issue where VS Code is complaining about not being able to find a module when trying to import an image from an assets directory within my project. Despite the fact that the image import works fine, I keep receiving the error message: ...
It's frustrating that in the example below, I encounter a typescript error despite the fact that the error is not logically possible to occur in the code. The function receives either Category1 or Category2 and when it returns the ComputedCategory, bo ...
export interface ValueParserResult { value: number, error: string } interface subParseResult { result: (string | number) [], error: string } class ValueParser { parse(eq: string, values: {[key: string] : number}, level?: number) : ValueParse ...
After configuring my tsconfig.json, I can now use short import paths in my code for brevity. This allows me to do things like import { FooService } from 'core' instead of the longer import { FooService } from '../../../core/services/foo/foo. ...
Is it possible to extract the unmatched results from a Regexp and store them in an array (essentially reversing the match)? The following code partially addresses this issue using the replace method: str = 'Lorem ipsum dolor is amet <a id="2" css ...
As I loop through the array named "fruits," which contains objects of type "FruitService" that I created, I want to display each element. However, when I delete them (I know it's strange, no database involved), they turn into type "undefined" and star ...
I offer a service: module app { export interface IOtherService { doAnotherThing(): string; } export class OtherService implements IOtherService { doAnotherThing() { return "hello."; }; } angular.mo ...
I am currently working on creating a function in Typescript that will map an object while ensuring that it retains the same keys. I have attempted different methods, but none seem to work as intended: function mapObject1<K extends PropertyKey, A, B>( ...
Is there a method to go back two steps when clicking on (click) goBack($event) instead of using just this.location.back()? I am looking for a way to access a list of locations in an array and cut out the last element. ...
Working with Vue 3, I'm setting up a form that will display text input fields corresponding to a fixed-length array of strings. Each field's v-model should connect to the respective string in the array. Here is my current code snippet for the vie ...
I need help converting an AngularJS Typescript Service into a Non-Singleton. Can anyone provide guidance on how to achieve this? (Note: This is not the same as other questions that focus on achieving this in JS) I have included some simple pseudo code be ...
Power BI Tutorial: Adding Formatting Options to the Circle Card Visual After completing step 8, I copied the code into my VS Code and encountered 2 error messages: Error message: "import VisualSettings - Module '"./settings"' has no e ...
As I delve into the Angular2 Quickstart, I stumbled upon a peculiar issue within app.component.js after compiling app.component.ts using tsc (version 1.8.2): if (d = decorators[i]) I am unable to pinpoint where I may have gone wrong in configuring the qu ...