> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# TypeScript Multi-line Comment
A multi-line comment in TypeScript is a lexical construct that instructs the compiler to ignore a sequence of characters spanning one or more lines. During lexical analysis, the TypeScript scanner tokenizes these blocks as `SyntaxKind.MultiLineCommentTrivia`. While comments are classified as trivia rather than standard Abstract Syntax Tree (AST) nodes, the compiler tracks their positional ranges and associates them with adjacent AST nodes.
**Syntax**
The construct is delimited by a starting `/*` sequence and a terminating `*/` sequence.
```typescript theme={"dark"}
/*
Line one of the comment block.
Line two of the comment block.
*/
let x: number = 10;
```
**Technical Characteristics**
* **Inline Masking:** Although termed "multi-line," the `/* */` delimiters can be utilized inline to omit specific tokens within a single statement without breaking the line.
```typescript theme={"dark"}
const price: number = 100;
const surcharge: number = 5;
const total: number = price + /* tax */ surcharge;
```
* **No Nesting Support:** TypeScript does not support nested multi-line comments. The scanner terminates the comment block at the first instance of `*/`. Any subsequent text or closing delimiters will be parsed as standard code, resulting in a syntax error.
```text theme={"dark"}
/*
Outer comment starts
/*
Inner comment starts (Scanner ignores this as a new delimiter)
*/ // <- This terminates the entire comment block
This text will cause a compiler error.
*/
```
* **Compilation Behavior and Node Elision:** Because comments are treated as trivia attached to specific AST nodes, their presence in the emitted JavaScript depends on the node they are attached to. If a multi-line comment is attached to a TypeScript-only node that is elided during compilation (such as a `type` alias or `interface`), the comment is also stripped from the emitted JavaScript, regardless of the `removeComments` compiler setting. For comments attached to standard JavaScript nodes, they are preserved by default unless the `removeComments` option in `tsconfig.json` is explicitly set to `true`.
* **Pinned Comments:** A multi-line comment starting with an exclamation mark `/*!` is classified as a pinned comment. This compiler feature ensures that comments containing critical metadata are intentionally preserved in the emitted JavaScript, even when the `removeComments` option is set to `true`. Note that pinned comments will still be stripped if attached to an elided TypeScript-only node.
```typescript theme={"dark"}
/*!
* Copyright (c) 2024. All rights reserved.
* This comment is preserved even if removeComments is true.
*/
const appVersion: string = "1.0.0";
```
* **JSDoc Parsing:** If a multi-line comment begins with a double asterisk `/**`, it is tokenized as standard multi-line trivia but is specifically recognized as a JSDoc comment. The TypeScript language service actively parses these specific blocks to extract type information and generate editor tooling (IntelliSense).
```typescript theme={"dark"}
/**
* This is parsed by the TypeScript Language Service.
*/
const initialize = (): void => {};
```
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