Learn React with TypeScript 3

Never

The never type represents something that would never occur and is typically used to specify unreachable areas of code. Again, this doesn't exist in JavaScript.

Time for an example:

1. Type the following code into the TypeScript playground:

function foreverTask(taskName: string): never {  while (true) {    console.log(`Doing ${taskName} over and over again ...`);  }}

The function invokes an infinite loop and never returns, and so we have given it a type annotation of never. This is different to void because void means it will return, but with no value.

In the preceding example, we used a JavaScript template literal to construct the string to log to the console. Template literals are enclosed by back-ticks (``) and can include a JavaScript ...