Variables

JavaScript variables give names to values. Start with const and reach for let only when the name needs to point somewhere else later.

Prefer const

01const name = "Mina";
02let lessonsRead = 3;

Change with intent

Use let for state that genuinely changes, such as a counter.

01let count = 0;
02count = count + 1;

Block scope

Both const and let belong to the nearest block. A value declared inside an if statement is unavailable outside it.

01const signedIn = true;
02
03if (signedIn) {
04  const message = "Welcome back";
05  console.log(message);
06}

Use names that describe the value's role: lessonCount is clearer than x. Boolean names often read well as questions such as isReady or hasAccess.

Destructure related values

01const profile = { name: "Mina", lessonsRead: 3 };
02const { name, lessonsRead } = profile;

Keep this

• Default to const.
• Use let for reassignment.
• Avoid var in modern code.
• Keep scope small and names specific.