If/else, switch, loops; truthiness & strict checks
Use if/else, switch, and loop patterns effectively; avoid pitfalls with truthiness and prefer strict checks.
If/else, switch, loops; truthiness & strict checks is a free TypeScript Academy lesson on CoddyKit — lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the TypeScript Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Overview
Goal: Build confidence with if/else, switch, and loops. You will also learn when a value is merely truthy versus strictly equal, so your branches reflect intent.
If/else basics
If/else branches on boolean expressions. Prefer explicit comparisons over loose checks to avoid surprises.
const n: number = 3;
if (n > 0) {
console.log("positive");
} else if (n === 0) {
console.log("zero");
} else {
console.log("negative");
}
switch with unions
switch works well with literal unions. Exhaustively handle cases to prevent fallthrough; add a default for safety.
const role: "admin" | "user" | "guest" = "admin";
switch (role) {
case "admin":
console.log("full access");
break;
case "user":
console.log("limited access");
break;
default:
console.log("guest view");
}
Loop patterns
Use classic for for indices and for...of to iterate values. Keep loops short and clear.
for (let i = 0; i < 3; i++) {
console.log("i =", i);
}
let sum = 0;
for (const v of [1, 2, 3]) {
sum += v;
}
console.log("sum =", sum);
Truthiness vs strict
A non-empty string like "0" is truthy, but it is not strictly equal to the number 0. Prefer === when meaning matters.
const x: any = "0";
if (x) {
console.log("truthy");
}
if (x === 0) {
console.log("number zero");
} else {
console.log("not number zero");
}
Best practices
Best practices:
- Prefer === / !== to avoid coercion.
- Keep branches short; extract functions for clarity.
- Use literal unions with switch for exhaustiveness.
- Favor for...of over index loops when you do not need the index.
Truthiness check
Quick check: Which statement is TRUE about truthiness vs strict checks?
Recap & next
Recap: You used if/else, switch, and loops; and learned the difference between truthy values and strict equality. Next: functions—params, defaults, and returns.
Frequently asked questions
Is the “If/else, switch, loops; truthiness & strict checks” lesson free?
Yes — the full text of “If/else, switch, loops; truthiness & strict checks” is free to read here on the web, and the TypeScript Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the TypeScript Academy course, upgrade to CoddyKit PRO.
What will I learn in “If/else, switch, loops; truthiness & strict checks”?
Use if/else, switch, and loop patterns effectively; avoid pitfalls with truthiness and prefer strict checks. You practise TypeScript Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start TypeScript Academy?
No prior experience is required. TypeScript Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “If/else, switch, loops; truthiness & strict checks” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this TypeScript Academy lesson?
Yes. Every TypeScript Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- If/else, switch, loops; truthiness & strict checks
- Functions: params, default/optional/rest; return types
- Arrow functions & contextual typing