> ## 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 Single-line Comment
A single-line comment in TypeScript is a lexical construct initiated by a double forward-slash (`//`) or triple forward-slash (`///`) that extends to the next line terminator (such as `\n` or `\r`) or the End of File (EOF). While standard single-line comments act as non-executable text, the TypeScript compiler explicitly parses specific single-line comments as pragmas or directives that directly alter type-checking evaluation, diagnostic reporting, and module resolution.
Standard single-line comments are scanned and processed during the lexical analysis and parsing phases. During the emit phase, the compiler (`tsc`) merely determines whether to strip or preserve them in the generated JavaScript output based on the `removeComments` boolean flag in the `tsconfig.json` configuration.
```typescript theme={"dark"}
// Standard single-line comment preceding a statement
const isCompiled: boolean = true;
const compilerTarget: string = "ES6"; // Inline single-line comment
```
**Compiler Directives**
Unlike standard JavaScript, TypeScript evaluates specific single-line comments as compiler instructions rather than ignored text. These are categorized into type-checking directives and triple-slash directives.
**Type-Checking Directives**
Initiated by `//` followed by specific `@ts-` flags, these comments alter the compiler's diagnostic behavior for the subsequent line or the entire file:
* `// @ts-expect-error`: Suppresses the compiler error on the following line, but emits a new error if no type error actually exists.
* `// @ts-ignore`: Unconditionally suppresses any compiler error on the following line.
* `// @ts-check`: Enables standard type-checking for a JavaScript (`.js`) file (equivalent to enabling the `checkJs` compiler option). Whether the checking is strict depends on the `strict` family of compiler options in the configuration.
* `// @ts-nocheck`: Disables type-checking for the entire file.
```typescript theme={"dark"}
// @ts-expect-error
const count: number = "string";
```
```typescript theme={"dark"}
// @ts-ignore
const data: boolean = 1;
```
```typescript theme={"dark"}
// @ts-nocheck
// Disables checking for this entire file, preventing errors on the following line
const uncheckedVariable: number = "string";
```
```javascript theme={"dark"}
// @ts-check
// Enables type-checking for this specific .js file
let checkedVariable = 10;
```
**Triple-Slash Directives**
A specialized single-line comment initiated by `///` containing a single XML tag. These must be placed at the top of the file (prior to any statements) and instruct the compiler on dependency resolution, type declarations, and compilation context.
```typescript theme={"dark"}
///
///
///
```
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