Libraries, Errors, Concepts, and the Full Map of a Software Project

A wide session today — some React and Node utilities, JavaScript error types worth knowing, a few important concepts, and then something genuinely useful at the end: the full picture of every category of tool a real software project actually needs. react-window — Don't Render What the User Can't See npm install react-window If you're rendering a list of 10,000 items, React doesn't need to put all 10,000 in the DOM at once. react-window handles virtualization — it only renders the items currently visible in the viewport and quietly swaps them out as the user scrolls. Same experience for the user, dramatically less work for the browser. Non-Null Assertion in TypeScript — The ! Operator When TypeScript isn't sure if a value might be null or undefined, it'll warn you. If you know it definitely isn't null, you can tell TypeScript to trust you using !: let text = document.getElementById('text')!; That ! at the end says "I promise this isn't null, stop worrying." TypeScript backs off. Use it