LiTScript shares configuration with the TypeScript compiler wherever possible. Additionally, it needs some settings to control what files are included in the documentation, what format is outputted, and so on.

These settings are defined in a configuration file called litsconfig.json which resides in the project root folder along with the usual tsconfig.json file. The same settings can also be specified as command line switches. These switches have the same names as the corresponding properties in the JSON file.

An example command line could look like this (each settings is described in the Options section):

lits --baseDir . --outDir temp  --updateToc

If a setting is not defined in the configuration or on command line, the default value takes effect. These are defined in the Defaults section. The precedence order for settings is thus:

  1. Command line
  2. litsconfig.json file
  3. Default value
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import * as fs from 'fs'
import * as ts from 'typescript'
import * as path from 'path'
import * as fm from './templates/front-matter'

Configuration files

The names of the configuration files are constants.

export const tsconfig = "tsconfig.json"
export const litsconfig = "litsconfig.json"


The available settings are defined in the Options interface. Options are case-insensitive both in JSON and command line. Keys are converted to lowercase before comparing them.

export interface Options {

Base Directory

We refer to the project root folder shortly as base directory. LiTScript expects to find the configuration files there.

    baseDir: string

Output Directory

The output directory is stored in the outDir property. A typical value for this is the docs/ folder under the base directory. From there the documentation files can be easily published to GitHub Pages.

    outDir: string

Output Format

The output format is either markdown or html. If markdown output is chosen the settings in the front matter are not used.

    outputFormat: 'markdown' | 'html'

Included Files

The processed TypeScript files are defined in tsconfig.json, so they need not to be specified here. Other types of input files you need to add to the files property. It contains a list of glob patterns that are relative to the base directory.

As an example, to include all files with the .md extension under directory instructions/, add pattern instructions/**.md to the list. The double asterisk wild card will find all the files, no matter how deep they are in the directory tree.

    files: string[]

Excluded Files

Sometimes you want to omit some files from the documentation. For example, you may want to skip TypeScript files that don't contain documentation. To achieve this you can list files to be excluded in the exclude array as glob patterns. This array is checked after the input files have been collected.

Note that all the TypeScript files in the project are compiled, only the documentation output is skipped. You can put other types of files in the exclude list, but usually it is simpler just to omit them from the files array.

    exclude: string[]

Silent Mode

Set the following flag to suppress output of status messages.

    silent: boolean

TOC File

The name of the table of contents a.k.a. TOC file is specified in the tocFile property. TOC file has to be placed in the outDir folder as the paths defined in it are relative to that directory.

    tocFile: string

Automatic TOC Update

LiTScript can automatically add new pages to the TOC file. To enable this, set the updateToc property to true. If you want to omit some files from TOC, you can add glob patterns that match their names to the excludeFromToc array.

    updateToc: boolean
    excludeFromToc: string[]

Dependency Graph

LiTScript can also create module dependency graph and save it in a JSON file. The name of the file is defined below. If undefined, the file is not produced.

    dependencyGraph: string


If you want to skip the bundling phase for HTML output, unset the following flag.

    bundle: boolean

Watch Mode

In watch mode LiTScript compiler runs in background and automatically regenerates documentation for changed files.

    watch: boolean

Serve Mode

LiTScript contains also a development web server that supports live reloading of changed files. When the serve setting is on, the web server is started. Note that the watch mode automatically turned on along with the serve mode.

You can customize the network options by changing the serveOptions object below.

    serve: boolean
    serveOptions: ServeOptions

Deployment Mode

The deployment mode controls whether debugging information needed for development is included with the generated JavaScript files.

    deployMode: 'dev' | 'prod'

Front Matter

Front matter is a template-specific configuration object that is defined in the template package. Front matter is settings for the default template can be found here.

    frontMatter: fm.FrontMatter

Serve Options

The network options used in serve mode are defined below.

export interface ServeOptions {

Host name or IP address. Typically or localhost.

    host: string

Listened port number. If omitted, port 8000 is used.

    port: number

Current Options and Defaults

The settings currently in effect can be read from this global variable.

var options: Options

Default values defined below are used for the settings that are not overridden in the configuration file or with the command line.

export const defaults: Options = {
    baseDir: ".",
    outDir: "./docs",
    outputFormat: 'html',
    files: ["**.md"],
    exclude: [ ".git", "node_modules" ],
    silent: false,
    tocFile: "toc.json",
    updateToc: false,
    excludeFromToc: [],
    dependencyGraph: "dependencies.json",
    bundle: true,
    watch: false,
    serve: false,
    serveOptions: {
        host: "",
        port: 8000
    deployMode: 'dev',
    frontMatter: fm.defaults

Other modules can access the effective settings using the function below.

export function getOptions(): Options {
    return options

The following function returns the path to the given file relative to the base directory.

export function getBaseRelativePath(filePath: string) {
    return path.relative(path.resolve(options.baseDir), filePath)

Setting Options

To set the options directly from outside the module, we provide this helper function. Note that we use the Partial utility type to make all properties optional, and merge the default values to them.

export function setOptions(opts: Partial<Options>) {
    options = opts as Options
    mergeOptions(defaults, options)

Reading Configuration File

The configuration file is read from JSON file into the global options object. After that, default values are merged to the object.

export function readOptionsFromFile(baseDir: string = "./") {
    let litsfile = path.resolve(baseDir, litsconfig)
    if (!fs.existsSync(litsfile))
        options = defaults
    else {
        let cont = fs.readFileSync(litsfile, 'utf8')
        options = JSON.parse(cont)
        mergeOptions(defaults, options)

Merging Configuration Objects

The following function recursively merges object properties. It only sets properties of the target object which are undefined. So, it does not override any properties already set.

export function mergeOptions(source: object, target: object) {
    for (const key in source)
        if (source.hasOwnProperty(key)) {
            let val = source[key]
            if (target.hasOwnProperty(key)) {
                let valType = typeof val
                if (typeof target[key] !== valType)
                    throw new SyntaxError(
                        `Invalid value for option "${key}". Expected ${valType}.`)
                if (valType === 'object' && !(val instanceof Array))
                    mergeOptions(val, target[key])
            else {
                if (val === undefined)
                    throw new Error(`Mandatory option "${key}" missing.`)
                target[key] = val

TypeScript Compiler Options

We store the compiler options read from tsconfig.json in a global variable. This variable can be read and written using the functions below.

var compilerOptions: ts.CompilerOptions

export function getCompilerOptions(): ts.CompilerOptions {
    return compilerOptions

export function setCompilerOptions(opts: ts.CompilerOptions) {
    compilerOptions = opts

Command Line Parsing

This helper function finds the field in the options object that corresponds to the specified command line switch. The search is case-insensitive. If no match is found, a CommandLineError exception is thrown.

function getOptionKey(option: string, optObj: object): string {
    for (const key in optObj)
        if (optObj.hasOwnProperty(key) &&
            key.toLowerCase() === option.toLowerCase())
            return key
    throw new CommandLineError("Unknown option: --" + option)

Command line parsing is done generically using the options object as the schema. Command line switches have the same names as the fields of the object. Depending on the type of the field the parsing works a bit differently. Strings are inputted as-is, booleans don't need an argument at all, and other types are read in as JSON.

export function parseCommandLine(args: string[], optObj: object) {
    let i = 0
    while (i < args.length) {
        let opt = args[i++]
        if (opt[0] != '-' || opt[1] != '-')
            throw new CommandLineError("Invalid command line argument: " + opt)
        let key = getOptionKey(opt.slice(2), optObj)
        let optype = typeof optObj[key]
        if (optype === 'boolean')
            optObj[key] = true
        else if (i == args.length)
            throw new CommandLineError("Value missing for option " + opt)
        else {
            let value = args[i++]
            optObj[key] = optype === 'string' ? value : JSON.parse(value)

Outputting command line options works also generically based on the options object.

export function printCommandLineOptions(optObj: object) {
    for (const key in optObj)
        if (optObj.hasOwnProperty(key))
            console.log(`--${key} \x1b[90m${JSON.stringify(optObj[key], 
                undefined, 4)}\x1b[0m`)

Command Line Errors

To distinguish command line errors from other types of errors, we define a new class extending the Error class.

export class CommandLineError extends Error {
    constructor(message: string) {