Ts Playground 37

To see how custom build steps modify your code. Why the Number "37" Matters

function echo<T>(value: T): T // If T is 'Self', then value is me. return value;

: The official TypeScript Playground allows you to test features across different versions. For example, TypeScript 3.7 introduced major features like Optional Chaining ( ?. ) and Nullish Coalescing ( ?? ), which you can still test by selecting "3.7.5" from the version dropdown menu. ts playground 37

let age: number | undefined = undefined; console.log(age ?? 0); // 0

A more advanced feature introduced in 3.7 was "Assertion Functions." This allows a function to assert that its argument is of a specific type, informing the compiler for the remainder of the scope. To see how custom build steps modify your code

type Add = (a: number, b: number) => number;

// 37: The playground where nothing compiled, but something understood. For example, TypeScript 3

const input = 0; const value = input || 10; // Result is 10, but we might have wanted 0.