flag-args

Command line arguments reader from specified flags, with readline prompt when value is not specified.

1) Arguments Reader

Initialisation

// Initialise from all function objects
const FlagArgs = require('flags-args-readline');
const args = FlagArgs.readArgs(['-f', '--file', '-t', '--target']);

// Initialise from only `readArgs` object
const { readArgs } = require('flags-args-readline');
const args = readArgs(['-f', '--file', '-t', '--target']);

Methods

1. has(params: string[]|string): bool

Return true if there is value of that given name.

Examples

/* COMMAND LINE:
  node test.js --target ./data.txt -a
*/

const args = readArgs(['-t', '--target', '-a']);
args.has('-t');               // false
args.has('--target');         // true
args.has(['-t', '--target']); // true
args.has('-a');               // false

2. get(params: string[]|string): string

Return value of specified argument name.

Examples

/* COMMAND LINE:
  node test.js --source ./data.txt -t ./out.txt
*/

const args = readArgs(
  ['-s', '--source', '-t', '--target']
);
args.get(['-s', '--source']); // "./data.txt"
args.get(['-t', '--target']); // "./out.txt"
args.get('-t');               // "./out.txt"
args.get('--target');         // undefined

3. getOrReadline(params: string[]|string): string

If there is value given in command line, return the value. Otherwise, show interactive line reader and read line from user's input, then return the value.

Examples

/* COMMAND LINE:
  node test.js -s ./data.txt
*/

const args = readArgs(
  ['-s', '--source', '-t', '--target']
);

temp = args.getOrReadline(['-s', '--source'], 'Where is source file?: ');
// ↑ "./data.txt"

temp = args.getOrReadline(['-t', '--target'], 'Where is target file?: ');
// ↑ Pause program, print "Where is target file?: " and then wait for user to input a line. After user has submit, read the line and return the value.

args.has(['-t', '--target']); // false
// ↑ using `getOrReadline` will not change aruments records in `args`, the value from readline is one-time use.

Accessing Values Directly

Examples

/* COMMAND LINE:
  node test.js -t ./out.txt
*/
const args = readArgs(
  ['-t', '--target', '-s', '--source']
);
args.args['-t'];        // "./out.txt"
args.args['--target'];  // undefined
args.args['-s'];        // undefined
args.args['--source'];  // undefined

---

2) Flags Reader

Initialisation

// Initialise from all function objects
const FlagArgs = require('flags-args-readline');
const args = FlagArgs.readFlags(['-a', '--all']);

// Initialise from only `readFlags` object
const { readFlags } = require('flags-args-readline');
const args = readFlags(['-a', '--all']);

Methods

has(string[]|string): bool

Return true if there is specified flag given from command line arguments. The logical operator, in case of array, is OR.

Examples

/* COMMAND LINE:
  node test.js -a
*/
const flags = readFlags(['-a', '--all']);
flags.has(['-a', '--all']); // true
flags.has('-a');            // true
flags.has('--all');         // false
flags.has('-t');            // false

Accessing Values Directly

Examples

/* COMMAND LINE:
  node test.js -a -u -t
*/
const flags = readFlags(['-a', '-u', '-s']);
flags.flags; // ['-a', '-u']

---

Using with npm command

Reminding that arguments passed from npm commands, such as npm start or npm run, those arguments belong to npm, not the node file. For this reason, to use the library with npm, the arguments should be passed after -- symbol.

Examples

const args = parseArgs(['-s', '-t']);
args.get('-s');

// From `npm run my-command -s something`     → undefined
// From `node run my-command -- -s something` → "something"

---