Ch 1 · Why TypeScript Is Worth Your Time · TypeScript

Topic 1 of 6 in TypeScript — Types That Protect Paid Work — 4 lessons.

The Bug the Client Finds First

Here is a bug that has cost freelancers real money. A client sends you their product data. You write a function that adds up an order. It works on your machine, on your test data. Two weeks after handover the client calls: totals are wrong on some orders, and they have already invoiced their customers.

TypeScript Is a Checker, Not a Runtime

This trips up almost everyone once. Browsers do not run TypeScript. Node does not run TypeScript. There is no TypeScript engine anywhere in production. What exists is a compiler, tsc, which does exactly two things:

Pin the Version: 5.9.3, Never latest

TypeScript has been rewritten. Version 7 is a new compiler built in Go — much faster, and different enough that a lot of advice written for version 5 no longer lines up with what it does or what it prints. If you install TypeScript today without saying which version you want, you get 7.

Check Yourself

All topics in TypeScript Beginner

1. Why TypeScript Is Worth Your Time
2. The Types You Will Use Every Day
3. Describing Your Data Once
4. Functions That State Their Terms
5. The Holes in the Fence
6. The Project You Set Up On Every Job