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. This is 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, and your progress syncs across the web and the CoddyKit app. The TypeScript Academy course includes 3 lessons in total.
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.
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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. 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. The TypeScript Academy course includes 3 lessons in total.
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, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 3.
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