Author: John Au-Yeung

Sometimes, we want to update TypeScript to latest version with npm.

In this article, we’ll look at how to update TypeScript to latest version with npm.

How to update TypeScript to latest version with npm?

To update TypeScript to latest version with npm, we install the typescript package with the latest version.

To do this, we run

npm install -g typescript@latest

We can also run

npm update

to update all packages including typescript.

Conclusion

To update TypeScript to latest version with npm, we install the typescript package with the latest version.

Sometimes, we want to perform string interpolation in TypeScript.

In this article, we’ll look at how to perform string interpolation in TypeScript.

How to perform string interpolation in TypeScript?

To perform string interpolation in TypeScript, we can create template literals like in JavaScript.

For instance, we write

const value = 100;
console.log(`The size is ${value}`);

to create the template literal with

`The size is ${value}`

We interpolate the value of the value variable in the string.

So we see 'The size is 100' logged.

Conclusion

To perform string interpolation in TypeScript, we can create template literals like in JavaScript.

To declare abstract method in TypeScript, we can use the abstract keyword.

For instance, we write

abstract class Animal {
  constructor(protected name: string) {}
  abstract makeSound(input: string): string;

  move(meters) {
    console.log(this.name, " moved");
  }
}

class Snake extends Animal {
  constructor(name: string) {
    super(name);
  }

  makeSound(input: string): string {
    return input;
  }

  move() {
    console.log("Slithering...");
    super.move(5);
  }
}

to create the Animal abstract class which have some methods that should be implemented when we create a class from it.

Then we create the Snake class that extends the Animal abstract class.

We implement all the methods in the abstract class in the class.

And we use super to reference the abstract class.

Sometimes, we want to return an empty Observable with Rxjs.

In this article, we’ll look at how to return an empty Observable with Rxjs.

How to return an empty Observable with Rxjs?

To return an empty Observable with Rxjs, we can use EMPTY or of.

For instance, we write

import { EMPTY, empty, of } from "rxjs";

EMPTY;
of({});

to import EMPTY which is an empty observable.

We can also call of with an empty object to return an empty observable.

Conclusion

To return an empty Observable with Rxjs, we can use EMPTY or of.

Sometimes, we want to make TypeScript interface properties optional.

In this article, we’ll look at how to make TypeScript interface properties optional.

How to make TypeScript interface properties optional?

To make TypeScript interface properties optional, we can add a ? after the property name.

For instance, we write

interface I {
  a: string;
  b?: any;
  c?: AnotherType;
}

to create the I interface with the b and c properties made optional by appending a ? to each property name.

Conclusion

To make TypeScript interface properties optional, we can add a ? after the property name.