Add more code comments

lib/arguments/command.js

@@ -4,6 +4,7 @@ import {getStartTime} from '../return/duration.js';
 import {joinCommand} from './escape.js';
 import {normalizeFdSpecificOption} from './specific.js';
 
+// Compute `result.command`, `result.escapedCommand` and `verbose`-related information
 export const handleCommand = (filePath, rawArguments, rawOptions) => {
 	const startTime = getStartTime();
 	const {command, escapedCommand} = joinCommand(filePath, rawArguments);

lib/arguments/cwd.js

@@ -3,6 +3,7 @@ import {resolve} from 'node:path';
 import process from 'node:process';
 import {safeNormalizeFileUrl} from './file-url.js';
 
+// Normalize `cwd` option
 export const normalizeCwd = (cwd = getDefaultCwd()) => {
 	const cwdString = safeNormalizeFileUrl(cwd, 'The "cwd" option');
 	return resolve(cwdString);
@@ -17,6 +18,7 @@ const getDefaultCwd = () => {
 	}
 };
 
+// When `cwd` option has an invalid value, provide with a better error message
 export const fixCwdError = (originalMessage, cwd) => {
 	if (cwd === getDefaultCwd()) {
 		return originalMessage;

lib/arguments/encoding-option.js

@@ -1,3 +1,4 @@
+// Validate `encoding` option
 export const validateEncoding = ({encoding}) => {
 	if (ENCODINGS.has(encoding)) {
 		return;

lib/arguments/escape.js

@@ -1,6 +1,7 @@
 import {platform} from 'node:process';
 import {stripVTControlCharacters} from 'node:util';
 
+// Compute `result.command` and `result.escapedCommand`
 export const joinCommand = (filePath, rawArguments) => {
 	const fileAndArguments = [filePath, ...rawArguments];
 	const command = fileAndArguments.join(' ');
@@ -10,6 +11,7 @@ export const joinCommand = (filePath, rawArguments) => {
 	return {command, escapedCommand};
 };
 
+// Remove ANSI sequences and escape control characters and newlines
 export const escapeLines = lines => stripVTControlCharacters(lines)
 	.split('\n')
 	.map(line => escapeControlCharacters(line))

lib/arguments/fd-options.js

@@ -1,5 +1,6 @@
 import {parseFd} from './specific.js';
 
+// Retrieve stream targeted by the `to` option
 export const getToStream = (destination, to = 'stdin') => {
 	const isWritable = true;
 	const {options, fileDescriptors} = SUBPROCESS_OPTIONS.get(destination);
@@ -13,6 +14,7 @@ export const getToStream = (destination, to = 'stdin') => {
 	return destinationStream;
 };
 
+// Retrieve stream targeted by the `from` option
 export const getFromStream = (source, from = 'stdout') => {
 	const isWritable = false;
 	const {options, fileDescriptors} = SUBPROCESS_OPTIONS.get(source);
@@ -26,6 +28,7 @@ export const getFromStream = (source, from = 'stdout') => {
 	return sourceStream;
 };
 
+// Keeps track of the options passed to each Execa call
 export const SUBPROCESS_OPTIONS = new WeakMap();
 
 const getFdNumber = (fileDescriptors, fdName, isWritable) => {

lib/arguments/file-url.js

@@ -1,5 +1,6 @@
 import {fileURLToPath} from 'node:url';
 
+// Allow some arguments/options to be either a file path string or a file URL
 export const safeNormalizeFileUrl = (file, name) => {
 	const fileString = normalizeFileUrl(file);
 
@@ -10,4 +11,5 @@ export const safeNormalizeFileUrl = (file, name) => {
 	return fileString;
 };
 
+// Same but also allows other values, e.g. `boolean` for the `shell` option
 export const normalizeFileUrl = file => file instanceof URL ? fileURLToPath(file) : file;

lib/arguments/options.js

@@ -10,6 +10,8 @@ import {normalizeCwd} from './cwd.js';
 import {normalizeFileUrl} from './file-url.js';
 import {normalizeFdSpecificOptions} from './specific.js';
 
+// Normalize the options object, and sometimes also the file paths and arguments.
+// Applies default values, validate allowed options, normalize them.
 export const normalizeOptions = (filePath, rawArguments, rawOptions) => {
 	rawOptions.cwd = normalizeCwd(rawOptions.cwd);
 	const [processedFile, processedArguments, processedOptions] = handleNodeOption(filePath, rawArguments, rawOptions);

lib/arguments/specific.js

@@ -2,6 +2,9 @@ import isPlainObject from 'is-plain-obj';
 import {STANDARD_STREAMS_ALIASES} from '../utils/standard-stream.js';
 import {verboseDefault} from '../verbose/info.js';
 
+// Some options can have different values for `stdout`/`stderr`/`fd3`.
+// This normalizes those to array of values.
+// For example, `{verbose: {stdout: 'none', stderr: 'full'}}` becomes `{verbose: ['none', 'none', 'full']}`
 export const normalizeFdSpecificOptions = options => {
 	const optionsCopy = {...options};
 
@@ -62,6 +65,7 @@ Please set the "stdio" option to ensure that file descriptor exists.`);
 	return fdNumber === 'all' ? [1, 2] : [fdNumber];
 };
 
+// Use the same syntax for fd-specific options and the `from`/`to` options
 export const parseFd = fdName => {
 	if (fdName === 'all') {
 		return fdName;
@@ -91,4 +95,5 @@ const DEFAULT_OPTIONS = {
 	stripFinalNewline: true,
 };
 
+// List of options which can have different values for `stdout`/`stderr`
 export const FD_SPECIFIC_OPTIONS = ['lines', 'buffer', 'maxBuffer', 'verbose', 'stripFinalNewline'];

lib/convert/add.js

@@ -4,6 +4,7 @@ import {createWritable} from './writable.js';
 import {createDuplex} from './duplex.js';
 import {createIterable} from './iterable.js';
 
+// Add methods to convert the subprocess to a stream or iterable
 export const addConvertedStreams = (subprocess, {encoding}) => {
 	const concurrentStreams = initializeConcurrentStreams();
 	subprocess.readable = createReadable.bind(undefined, {subprocess, concurrentStreams, encoding});

lib/convert/duplex.js

@@ -15,7 +15,7 @@ import {
 	onWritableDestroy,
 } from './writable.js';
 
-// Create a `Duplex` stream combining both
+// Create a `Duplex` stream combining both `subprocess.readable()` and `subprocess.writable()`
 export const createDuplex = ({subprocess, concurrentStreams, encoding}, {from, to, binary: binaryOption = true, preserveNewlines = true} = {}) => {
 	const binary = binaryOption || BINARY_ENCODINGS.has(encoding);
 	const {subprocessStdout, waitReadableDestroy} = getSubprocessStdout(subprocess, from, concurrentStreams);

lib/convert/iterable.js

@@ -2,6 +2,7 @@ import {BINARY_ENCODINGS} from '../arguments/encoding-option.js';
 import {getFromStream} from '../arguments/fd-options.js';
 import {iterateOnSubprocessStream} from '../io/iterate.js';
 
+// Convert the subprocess to an async iterable
 export const createIterable = (subprocess, encoding, {
 	from,
 	binary: binaryOption = false,

lib/io/contents.js

@@ -6,6 +6,7 @@ import {iterateForResult} from './iterate.js';
 import {handleMaxBuffer} from './max-buffer.js';
 import {getStripFinalNewline} from './strip-newline.js';
 
+// Retrieve `result.stdout|stderr|all|stdio[*]`
 export const getStreamOutput = async ({stream, onStreamEnd, fdNumber, encoding, buffer, maxBuffer, lines, allMixed, stripFinalNewline, verboseInfo, streamInfo: {fileDescriptors}}) => {
 	if (shouldLogOutput({
 		stdioItems: fileDescriptors[fdNumber]?.stdioItems,
@@ -91,6 +92,7 @@ export const getBufferedData = async streamPromise => {
 	}
 };
 
+// Ensure we are returning Uint8Arrays when using `encoding: 'buffer'`
 const handleBufferedData = ({bufferedData}) => isArrayBuffer(bufferedData)
 	? new Uint8Array(bufferedData)
 	: bufferedData;

lib/io/max-buffer.js

@@ -1,6 +1,8 @@
 import {MaxBufferError} from 'get-stream';
 import {getStreamName} from '../utils/standard-stream.js';
 
+// When the `maxBuffer` option is hit, a MaxBufferError is thrown.
+// The stream is aborted, then specific information is kept for the error message.
 export const handleMaxBuffer = ({error, stream, readableObjectMode, lines, encoding, fdNumber}) => {
 	if (!(error instanceof MaxBufferError)) {
 		throw error;
@@ -32,6 +34,7 @@ const getMaxBufferUnit = (readableObjectMode, lines, encoding) => {
 	return 'characters';
 };
 
+// Error message when `maxBuffer` is hit
 export const getMaxBufferMessage = (error, maxBuffer) => {
 	const {streamName, threshold, unit} = getMaxBufferInfo(error, maxBuffer);
 	return `Command's ${streamName} was larger than ${threshold} ${unit}`;
@@ -47,6 +50,9 @@ const getMaxBufferInfo = (error, maxBuffer) => {
 	return {streamName: getStreamName(fdNumber), threshold: maxBuffer[fdNumber], unit};
 };
 
+// The only way to apply `maxBuffer` with `spawnSync()` is to use the native `maxBuffer` option Node.js provides.
+// However, this has multiple limitations, and cannot behave the exact same way as the async behavior.
+// When the `maxBuffer` is hit, a `ENOBUFS` error is thrown.
 export const isMaxBufferSync = (resultError, output, maxBuffer) => resultError?.code === 'ENOBUFS'
 	&& output !== null
 	&& output.some(result => result !== null && result.length > getMaxBufferSync(maxBuffer));

lib/io/output-async.js

@@ -32,7 +32,7 @@ export const pipeOutputAsync = (subprocess, fileDescriptors, controller) => {
 	}
 };
 
-// `subprocess.stdin|stdout|stderr|stdio` is directly mutated.
+// When using transforms, `subprocess.stdin|stdout|stderr|stdio` is directly mutated
 const pipeTransform = (subprocess, stream, direction, fdNumber) => {
 	if (direction === 'output') {
 		pipeStreams(subprocess.stdio[fdNumber], stream);
@@ -50,6 +50,8 @@ const pipeTransform = (subprocess, stream, direction, fdNumber) => {
 
 const SUBPROCESS_STREAM_PROPERTIES = ['stdin', 'stdout', 'stderr'];
 
+// Most `std*` option values involve piping `subprocess.std*` to a stream.
+// The stream is either passed by the user or created internally.
 const pipeStdioItem = ({subprocess, stream, direction, fdNumber, inputStreamsGroups, controller}) => {
 	if (stream === undefined) {
 		return;

lib/io/output-sync.js

@@ -67,6 +67,7 @@ const transformOutputResultSync = ({result, fileDescriptors, fdNumber, state, is
 	}
 };
 
+// Applies transform generators to `stdout`/`stderr`
 const runOutputGeneratorsSync = (chunks, stdioItems, encoding, state) => {
 	try {
 		return runGeneratorsSync(chunks, stdioItems, encoding, false);
@@ -76,6 +77,9 @@ const runOutputGeneratorsSync = (chunks, stdioItems, encoding, state) => {
 	}
 };
 
+// The contents is converted to three stages:
+//  - serializedResult: used when the target is a file path/URL or a file descriptor (including 'inherit')
+//  - finalResult/returnedResult: returned as `result.std*`
 const serializeChunks = ({chunks, objectMode, encoding, lines, stripFinalNewline, fdNumber}) => {
 	if (objectMode) {
 		return {serializedResult: chunks};
@@ -93,6 +97,7 @@ const serializeChunks = ({chunks, objectMode, encoding, lines, stripFinalNewline
 	return {serializedResult};
 };
 
+// When the `std*` target is a file path/URL or a file descriptor
 const writeToFiles = (serializedResult, stdioItems) => {
 	for (const {type, path} of stdioItems) {
 		if (FILE_TYPES.has(type)) {

lib/io/pipeline.js

@@ -1,7 +1,7 @@
 import {finished} from 'node:stream/promises';
 import {isStandardStream} from '../utils/standard-stream.js';
 
-// Like `Stream.pipeline(source, destination)`, but does not destroy standard streams.
+// Similar to `Stream.pipeline(source, destination)`, but does not destroy standard streams
 export const pipeStreams = (source, destination) => {
 	source.pipe(destination);
 	onSourceFinish(source, destination);

lib/io/strip-newline.js

@@ -1,9 +1,12 @@
 import stripFinalNewlineFunction from 'strip-final-newline';
 
+// Apply `stripFinalNewline` option, which applies to `result.stdout|stderr|all|stdio[*]`.
+// If the `lines` option is used, it is applied on each line, but using a different function.
 export const stripNewline = (value, {stripFinalNewline}, fdNumber) => getStripFinalNewline(stripFinalNewline, fdNumber) && value !== undefined && !Array.isArray(value)
 	? stripFinalNewlineFunction(value)
 	: value;
 
+// Retrieve `stripFinalNewline` option value, including with `subprocess.all`
 export const getStripFinalNewline = (stripFinalNewline, fdNumber) => fdNumber === 'all'
 	? stripFinalNewline[1] || stripFinalNewline[2]
 	: stripFinalNewline[fdNumber];

lib/methods/command.js

@@ -1,6 +1,10 @@
+// Main logic for `execaCommand()`
 export const mapCommandAsync = ({file, commandArguments}) => parseCommand(file, commandArguments);
+
+// Main logic for `execaCommandSync()`
 export const mapCommandSync = ({file, commandArguments}) => ({...parseCommand(file, commandArguments), isSync: true});
 
+// Convert `execaCommand(command)` into `execa(file, ...commandArguments)`
 const parseCommand = (command, unusedArguments) => {
 	if (unusedArguments.length > 0) {
 		throw new TypeError(`The command and its arguments must be passed as a single string: ${command} ${unusedArguments}.`);

lib/methods/create.js

@@ -5,6 +5,11 @@ import {execaCoreSync} from './main-sync.js';
 import {execaCoreAsync} from './main-async.js';
 import {mergeOptions} from './bind.js';
 
+// Wraps every exported methods to provide the following features:
+//  - template string syntax: execa`command argument`
+//  - options binding: boundExeca = execa(options)
+//  - optional argument/options: execa(file), execa(file, args), execa(file, options), execa(file, args, options)
+// `mapArguments()` and `setBoundExeca()` allows for method-specific logic.
 export const createExeca = (mapArguments, boundOptions, deepOptions, setBoundExeca) => {
 	const createNested = (mapArguments, boundOptions, setBoundExeca) => createExeca(mapArguments, boundOptions, deepOptions, setBoundExeca);
 	const boundExeca = (...execaArguments) => callBoundExeca({

lib/methods/main-async.js

@@ -19,6 +19,7 @@ import {waitForSubprocessResult} from '../resolve/wait-subprocess.js';
 import {addConvertedStreams} from '../convert/add.js';
 import {mergePromise} from './promise.js';
 
+// Main shared logic for all async methods: `execa()`, `execaCommand()`, `$`, `execaNode()`
 export const execaCoreAsync = (rawFile, rawArguments, rawOptions, createNested) => {
 	const {file, commandArguments, command, escapedCommand, startTime, verboseInfo, options, fileDescriptors} = handleAsyncArguments(rawFile, rawArguments, rawOptions);
 	const {subprocess, promise} = spawnSubprocessAsync({
@@ -42,6 +43,7 @@ export const execaCoreAsync = (rawFile, rawArguments, rawOptions, createNested)
 	return subprocess;
 };
 
+// Compute arguments to pass to `child_process.spawn()`
 const handleAsyncArguments = (rawFile, rawArguments, rawOptions) => {
 	const {command, escapedCommand, startTime, verboseInfo} = handleCommand(rawFile, rawArguments, rawOptions);
 
@@ -65,7 +67,8 @@ const handleAsyncArguments = (rawFile, rawArguments, rawOptions) => {
 	}
 };
 
-// Prevent passing the `timeout` option directly to `child_process.spawn()`
+// Options normalization logic specific to async methods.
+// Prevent passing the `timeout` option directly to `child_process.spawn()`.
 const handleAsyncOptions = ({timeout, signal, cancelSignal, ...options}) => {
 	if (signal !== undefined) {
 		throw new TypeError('The "signal" option has been renamed to "cancelSignal" instead.');
@@ -120,6 +123,7 @@ const spawnSubprocessAsync = ({file, commandArguments, options, startTime, verbo
 	return {subprocess, promise};
 };
 
+// Asynchronous logic, as opposed to the previous logic which can be run synchronously, i.e. can be returned to user right away
 const handlePromise = async ({subprocess, options, startTime, verboseInfo, fileDescriptors, originalStreams, command, escapedCommand, controller}) => {
 	const context = {timedOut: false};
 

lib/methods/main-sync.js

@@ -12,6 +12,7 @@ import {logEarlyResult} from '../verbose/complete.js';
 import {getAllSync} from '../resolve/all-sync.js';
 import {getExitResultSync} from '../resolve/exit-sync.js';
 
+// Main shared logic for all sync methods: `execaSync()`, `execaCommandSync()`, `$.sync()`
 export const execaCoreSync = (rawFile, rawArguments, rawOptions) => {
 	const {file, commandArguments, command, escapedCommand, startTime, verboseInfo, options, fileDescriptors} = handleSyncArguments(rawFile, rawArguments, rawOptions);
 	const result = spawnSubprocessSync({
@@ -27,6 +28,7 @@ export const execaCoreSync = (rawFile, rawArguments, rawOptions) => {
 	return handleResult(result, verboseInfo, options);
 };
 
+// Compute arguments to pass to `child_process.spawnSync()`
 const handleSyncArguments = (rawFile, rawArguments, rawOptions) => {
 	const {command, escapedCommand, startTime, verboseInfo} = handleCommand(rawFile, rawArguments, rawOptions);
 
@@ -51,8 +53,10 @@ const handleSyncArguments = (rawFile, rawArguments, rawOptions) => {
 	}
 };
 
+// Options normalization logic specific to sync methods
 const normalizeSyncOptions = options => options.node && !options.ipc ? {...options, ipc: false} : options;
 
+// Options validation logic specific to sync methods
 const validateSyncOptions = ({ipc, detached, cancelSignal}) => {
 	if (ipc) {
 		throwInvalidSyncOption('ipc: true');
@@ -128,6 +132,7 @@ const runSubprocessSync = ({file, commandArguments, options, command, escapedCom
 	}
 };
 
+// The `encoding` option is handled by Execa, not by `child_process.spawnSync()`
 const normalizeSpawnSyncOptions = ({encoding, maxBuffer, ...options}) => ({...options, encoding: 'buffer', maxBuffer: getMaxBufferSync(maxBuffer)});
 
 const getSyncResult = ({error, exitCode, signal, timedOut, isMaxBuffer, stdio, all, options, command, escapedCommand, startTime}) => error === undefined

lib/methods/node.js

@@ -2,6 +2,7 @@ import {execPath, execArgv} from 'node:process';
 import {basename, resolve} from 'node:path';
 import {safeNormalizeFileUrl} from '../arguments/file-url.js';
 
+// `execaNode()` is a shortcut for `execa(..., {node: true})`
 export const mapNode = ({options}) => {
 	if (options.node === false) {
 		throw new TypeError('The "node" option cannot be false with `execaNode()`.');
@@ -10,6 +11,9 @@ export const mapNode = ({options}) => {
 	return {options: {...options, node: true}};
 };
 
+// Applies the `node: true` option, and the related `nodePath`/`nodeOptions` options.
+// Modifies the file commands/arguments to ensure the same Node binary and flags are re-used.
+// Also adds `ipc: true` and `shell: false`.
 export const handleNodeOption = (file, commandArguments, {
 	node: shouldHandleNode = false,
 	nodePath = execPath,

lib/methods/parameters.js

@@ -1,6 +1,8 @@
 import isPlainObject from 'is-plain-obj';
 import {safeNormalizeFileUrl} from '../arguments/file-url.js';
 
+// The command `arguments` and `options` are both optional.
+// This also does basic validation on them and on the command file.
 export const normalizeParameters = (rawFile, rawArguments = [], rawOptions = {}) => {
 	const filePath = safeNormalizeFileUrl(rawFile, 'First argument');
 	const [commandArguments, options] = isPlainObject(rawArguments)

lib/methods/script.js

@@ -1,15 +1,22 @@
+// Sets `$.sync` and `$.s`
 export const setScriptSync = (boundExeca, createNested, boundOptions) => {
 	boundExeca.sync = createNested(mapScriptSync, boundOptions);
 	boundExeca.s = boundExeca.sync;
 };
 
+// Main logic for `$`
 export const mapScriptAsync = ({options}) => getScriptOptions(options);
+
+// Main logic for `$.sync`
 const mapScriptSync = ({options}) => ({...getScriptOptions(options), isSync: true});
 
+// `$` is like `execa` but with script-friendly options: `{stdin: 'inherit', preferLocal: true}`
 const getScriptOptions = options => ({options: {...getScriptStdinOption(options), ...options}});
 
 const getScriptStdinOption = ({input, inputFile, stdio}) => input === undefined && inputFile === undefined && stdio === undefined
 	? {stdin: 'inherit'}
 	: {};
 
+// When using $(...).pipe(...), most script-friendly options should apply to both commands.
+// However, some options (like `stdin: 'inherit'`) would create issues with piping, i.e. cannot be deep.
 export const deepScriptOptions = {preferLocal: true};