Typescript Programming Tutorials, Guides & Best Practices

function identity<T>(arg: T): T {
  return arg;
}

const result = identity<string>("Hello TypeScript");

You can constrain generics to ensure that the types passed to them meet certain requirements. This is useful when you want to make sure that the generic type has certain properties or methods.

type IsString<T> = T extends string ? 'Yes' : 'No';

type A = IsString<string>; // 'Yes'
type B = IsString<number>; // 'No'

This type checks whether a given type is a string and returns 'Yes' or 'No' accordingly.

let disposable = vscode.commands.registerCommand('extension.showHelloWorld', () => {
    const greeting = vscode.workspace.getConfiguration().get('myExtension.greeting', 'Hello, World!');
    vscode.window.showInformationMessage(greeting);
});

Now users can change the greeting message through the VS Code settings.

TypeScript allows you to add type annotations to variables, function parameters, and return types:

let isDone: boolean = false;
let count: number = 10;
let name: string = "Alice";

function add(a: number, b: number): number {
  return a + b;
}

  function add(a: number, b: number): number {
    return a + b;
  }

• Use any as a Temporary Fix: If you encounter complex code where you're unsure of the type, you can temporarily use any. However, this should be minimized and revisited later.