prettier-linter-helpers

1.0.1 verified Sat Apr 25 auth: no javascript maintenance

Utilities to help expose prettier output in linting tools. Version 1.0.1 provides two helper functions: showInvisibles and generateDifferences. Extracted from eslint-plugin-prettier v2.7.0, it is stable but rarely updated. Key differentiator: offers a shared, tested way to compute and display differences from prettier output, avoiding duplication across multiple linter integrations. Lightweight with no dependencies, but relies on prettier being installed separately.

Common errors

error TypeError: (0 , prettier_linter_helpers.showInvisibles) is not a function ↓

cause Using CommonJS require incorrectly with ES module bundlers like Webpack.

fix

Change to: import { showInvisibles } from 'prettier-linter-helpers'

error Module not found: Can't resolve 'prettier-linter-helpers' ↓

cause Package not installed or not in node_modules.

fix

Run: npm install prettier-linter-helpers

error Cannot read property 'showInvisibles' of undefined ↓

cause Attempting to access a named export as a property of the default export.

fix

Use named import: import { showInvisibles } from 'prettier-linter-helpers'

Warnings

gotcha generateDifferences returns an array of difference objects that are not deeply immutable; do not mutate them. ↓

fix Treat the returned differences as read-only; copy if modification needed.

deprecated Package is in maintenance mode; no new features are planned. ↓

fix Consider directly using prettier's own diffing utilities if more advanced features are needed.

gotcha showInvisibles is intended for display purposes only; do not use it for programmatic string manipulation. ↓

fix Use the original string for any logic; showInvisibles changes characters (e.g., space to ·).

Install

npm install prettier-linter-helpers

yarn add prettier-linter-helpers

pnpm add prettier-linter-helpers

Imports

showInvisibles

wrong

const showInvisibles = require('prettier-linter-helpers').showInvisibles

correct

import { showInvisibles } from 'prettier-linter-helpers'

ESM import works in Node >=12; CommonJS require also works as package supports both.

generateDifferences
wrong
```
import generateDifferences from 'prettier-linter-helpers'
```
correct
```
import { generateDifferences } from 'prettier-linter-helpers'
```
This is a named export, not default. CommonJS: const { generateDifferences } = require('prettier-linter-helpers').

package

wrong

const helpers = require('prettier-linter-helpers'); helpers.default.showInvisibles

correct

import * as helpers from 'prettier-linter-helpers'

There is no default export; use namespace import if you want both.

types
```
import type { Difference } from 'prettier-linter-helpers'
```
TypeScript types are included; 'Difference' is the type of items in the array returned by generateDifferences.

Quickstart

Imports the two helper functions, shows use of showInvisibles to make whitespace visible, and generateDifferences to compare two strings.

import { showInvisibles, generateDifferences } from 'prettier-linter-helpers';

const source = 'const x = 1;\n';
const prettierSource = 'const x = 1;\n';

// Show invisible characters (tab, space, newline)
const visible = showInvisibles(source);
console.log(visible);
// 'const x = 1;·\n'

// Generate differences between source and prettierSource
const diffs = generateDifferences(source, prettierSource);
console.log(diffs);
// []

// Example with a difference
const source2 = 'const x = 1';
const prettierSource2 = 'const x = 1;\n';
const diffs2 = generateDifferences(source2, prettierSource2);
console.log(diffs2);
// [ { offset: 11, operation: 'insert', insertText: ';\n' } ]