@esmkit/code-frame

Generate errors that contain a code frame that point to source locations.

Installation

bun add @esmkit/code-frame

Usage

codeFrameColumns

The codeFrameColumns function allows you to decorate a code snipped with line numbers and with a marker pointing to a specific location.

It will also optionally highlight your code, defaulting to what is supported by the output terminal.

import { codeFrameColumns } from "@esmkit/code-frame";

const rawLines = `class Foo {
  constructor()
}`;
const location = { start: { line: 2, column: 16 } };

const result = codeFrameColumns(rawLines, location, {
  /* options */
});

console.log(result);

1 | class Foo {
> 2 |   constructor()
    |                ^
  3 | }

If the column number is not known, you may omit it.

You can also pass an end hash in location.

import { codeFrameColumns } from "@esmkit/code-frame";

const rawLines = `class Foo {
  constructor() {
    console.log("hello");
  }
}`;
const location = {
  start: { line: 2, column: 17 },
  end: { line: 4, column: 3 },
};

const result = codeFrameColumns(rawLines, location, {
  /* options */
});

console.log(result);

  1 | class Foo {
> 2 |   constructor() {
    |                 ^
> 3 |     console.log("hello");
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
> 4 |   }
    | ^^^
  5 | };

Options

• highlightCode: boolean, defaults to false. Toggles syntax highlighting the code as JavaScript for terminals.
• linesAbove: number, defaults to 2. Adjust the number of lines to show above the error.
• linesBelow: number, defaults to 3. Adjust the number of lines to show below the error.
• forceColor: boolean, defaults to false. Enable this to forcibly syntax highlight the code as JavaScript (for non-terminals); overrides highlightCode.
• message: string, otherwise nothing

Pass in a string to be displayed inline (if possible) next to the highlighted location in the code. If it can't be positioned inline, it will be placed above the code frame.

1 | class Foo {
> 2 |   constructor()
  |                ^ Missing {
3 | };

License

MIT © BILLGO. See LICENSE for details.