API.md

API

You can use tslint-to-eslint-config programmatically in your Node apps. It provides a convertTSLintConfig function to find relevant configurations on disk and output the generated ESLint configuration.

convertTSLintConfig

import { convertTSLintConfig } from "tslint-to-eslint-config";

const result = await convertTSLintConfig();

Finds relevant configurations on disk and outputs the generated ESLint configuration.

Optionally takes in the same settings you can provide via the CLI:

• config: Output ESLint configuration file path (default: .eslintrc.js).
• eslint: Original ESLint configuration file path (default: .eslintrc.js).
• package: Original packages configuration file path (default: package.json).
• prettier: Whether to add eslint-config-prettier to the plugins list.
• tslint: Original TSLint configuration file path (default: tslint.json).
• typescript: Original TypeScript configuration file path (default: tsconfig.json).

import { convertTSLintConfig } from "tslint-to-eslint-config";

const result = await convertTSLintConfig({
    config: "./path/to/output/eslintrc.js",
    eslint: "./path/to/input/eslintrc.js",
    package: "./path/to/package.json", 
    prettier: true, // Prettier: highly recommended!
    tslint: "./path/to/tslint.json", 
    typescript: "./path/to/tsconfig.json", 
});

If the TSLint configuration or any manually specified configurations fail to read from disk, the result will contain:

• complaints: String complaints describing the errors.
• status: ResultStatus.ConfigurationError (2).

If no error is detected, the result will contain:

• data: Resultant ESLint configuration as:
  • formatted: Stringified result per the output config path's file type.
  • raw: Plain old JavaScript object.
• status: ResultStatus.Succeeded (0).

import { convertTSLintConfig, ResultStatus } from "tslint-to-eslint-config";

const result = await convertTSLintConfig({ /* ... */ });

if (result.status !== ResultStatus.Succeeded) {
    console.info("Oh no!");
    console.error(result.complaints.join("\n"));
} else {
    console.info("Hooray!");
    console.log(result.data.formatted);
    console.log(result.data.raw);
}

See the provided .d.ts TypeScript typings for full descriptions of inputs and outputs.

Standalone Lint Conversion API

Portions of the individual lint conversion steps within convertTSLintConfig are each available as exported functions as well.

• findOriginalConfigurations takes in an object of original configuration locations and retrieves their raw and computed contents.
  • findReportedConfiguration runs a config print command and parses its output as JSON.
• createESLintConfiguration creates an raw output ESLint configuration summary from those input configuration values.
  • joinConfigConversionResults turns a raw ESLint configuration summary into ESLint's configuration shape.
  • formatOutput prints that formatted output into a string per the output file extension.

findOriginalConfigurations

Reading in from the default file locations, including .eslintrc.js:

import { findOriginalConfigurations } from "tslint-to-eslint-config";

const originalConfigurations = await findOriginalConfigurations();

Overriding some configuration file locations to read from:

import { findOriginalConfigurations } from "tslint-to-eslint-config";

const originalConfigurations = await findOriginalConfigurations({
    config: "./path/to/.eslintrc.json",
    tslint: "./another/path/to/tslint.custom.json",
});

findReportedConfiguration

Retrieving the reported contents of a TSLint configuration:

import { findReportedConfiguration } from "tslint-to-eslint-config";

const full = await findReportedConfiguration("npx tslint --print-config", "./tslint.json");

createESLintConfiguration

Generating an ESLint configuration from the contents of a local tslint.json:

import { createESLintConfiguration, findReportedConfiguration } from "tslint-to-eslint-config";

const summarizedConfiguration = await createESLintConfiguration({
    tslint: {
        full: await findReportedConfiguration("npx tslint --print-config", "./tslint.json"),
        raw: require("./tslint.json"),
    },
});

Using the full configuration values from disk:

import { createESLintConfiguration, findOriginalConfigurations } from "tslint-to-eslint-config";

const originalConfigurations = await findOriginalConfigurations();
const summarizedConfiguration = await createESLintConfiguration(originalConfigurations);

const raw = joinConfigConversionResults(summarizedConfiguration, originalConfigurations.data);

const formatted = formatOutput("eslintrc.js", raw);

Standalone Comment Conversion API

The individual per-file conversion logic within convertComments is available as a standalone function:

convertFileComments

Takes in a file's content and path, and returns the content with inline lint comments converted from TSLint to ESLint:

import { convertFileComments } from "tslint-to-eslint-config";

// "// eslint-disable-next-line"
const newContents = convertFileComments({
    fileContent: "// tslint:disable-next-line",
    filePath: "a.ts",
});

If using this function across multiple files, pass it a ruleCommentsCache so it can skip some conversion calculations for a mild performance boost:

import { convertFileComments } from "tslint-to-eslint-config";

const ruleCommentsCache = new Map<string, string[]>();

const firstNewContents = convertFileComments({
    fileContent: "...",
    filePath: "a.ts",
    ruleCommentsCache,
});

const secondNewContents = convertFileComments({
    fileContent: "...",
    filePath: "b.tsx",
    ruleCommentsCache,
});

If running alongside a lint config conversion, pass the filled out ruleEquivalents map for more accurate conversions of TSLint rules whose ESLint equivalents change on different arguments:

import { convertFileComments, createESLintConfiguration } from "tslint-to-eslint-config";

const { ruleEquivalents } = await createESLintConfiguration(originalConfigurations);

convertFileComments({
    fileContent: "...",
    filePath: "a.ts",
    ruleEquivalents,
})