JavaScript Statements
A JavaScript program is a list of statements executed by the browser in the order they're written. Each statement typically performs one instruction, like assigning a value or calling a function.
Statements are usually separated by semicolons, though JavaScript can often infer them automatically via a mechanism called Automatic Semicolon Insertion (ASI).
Statement basics
A statement can be a variable declaration, an assignment, a function call, or a control structure like if or for. Multiple statements form a script.
Semicolons
While ASI allows omitting semicolons in many cases, relying on it can cause subtle bugs. Best practice is to always end statements with a semicolon.
let x = 5;
let y = 6;
let z = x + y;
console.log(z);11Three statements execute in sequence, then the result is logged.
{
let a = 1;
let b = 2;
console.log(a + b);
}3Curly braces group statements into a block.
Key points
- Statements execute top to bottom, in order.
- Semicolons separate statements (recommended even though optional).
- Curly braces `{}` group statements into blocks.
- Whitespace and line breaks are mostly ignored by the interpreter.