Nodejs command line parameter handling module commander USES the instance

  • 2020-03-30 03:58:09
  • OfStack

Admittedly, the previous deal was to use the built-in process.agrv, which worked, but didn't work well, so tj wrote a "my god" that was completely overgrown:

1, install,

npm install commander

2. Option resolution

Options with commander are defined with the. Option () method, also serving as documentation for the Options. The example below parses args and Options from process.argv, Leaving remaining args as the program. Args array which were not consumed by options.

#!/usr/bin/env node
 * Module dependencies.
var program = require('commander');
  .option('-p, --peppers', 'Add peppers')
  .option('-P, --pineapple', 'Add pineapple')
  .option('-b, --bbq', 'Add bbq sauce')
  .option('-c, --cheese [type]', 'Add the specified type of cheese [marble]', 'marble')
console.log('you ordered a pizza with:');
if (program.peppers) console.log('  - peppers');
if (program.pineapple) console.log('  - pineapple');
if (program.bbq) console.log('  - bbq');
console.log('  - %s cheese', program.cheese);

Short flags may be passed as a single arg, for example - ABC is equivalent to - a - b - c - word options to as " � the template engine" - are camel - cased, becoming the program. The templateEngine etc.

3. Automatically generate help information

$ ./examples/pizza --help
  Usage: pizza [options]
    -V, --version        output the version number
    -p, --peppers        Add peppers
    -P, --pineapple      Add pineapple
    -b, --bbq            Add bbq sauce
    -c, --cheese <type>  Add the specified type of cheese [marble]
    -h, --help           output usage information

Of course, you can also manually generate:

#!/usr/bin/env node
 * Module dependencies.
var program = require('../');
function list(val) {
  return val.split(',').map(Number);
  .option('-f, --foo', 'enable some foo')
  .option('-b, --bar', 'enable some bar')
  .option('-B, --baz', 'enable some baz');
// must be before .parse() since
// node's emit() is immediate
program.on('--help', function(){
  console.log('  Examples:');
  console.log('    $ custom-help --help');
  console.log('    $ custom-help -h');

4. Give a complete example

function range(val) {
  return val.split('..').map(Number);
function list(val) {
  return val.split(',');
function collect(val, memo) {
  return memo;
function increaseVerbosity(v, total) {
  return total + 1;
  .usage('[options] <file ...>')
  .option('-i, --integer <n>', 'An integer argument', parseInt)
  .option('-f, --float <n>', 'A float argument', parseFloat)
  .option('-r, --range <a>..<b>', 'A range', range)
  .option('-l, --list <items>', 'A list', list)
  .option('-o, --optional [value]', 'An optional value')
  .option('-c, --collect [value]', 'A repeatable value', collect, [])
  .option('-v, --verbose', 'A value that can be increased', increaseVerbosity, 0)
console.log(' int: %j', program.integer);
console.log(' float: %j', program.float);
console.log(' optional: %j', program.optional);
program.range = program.range || [];
console.log(' range: %j..%j', program.range[0], program.range[1]);
console.log(' list: %j', program.list);
console.log(' collect: %j', program.collect);
console.log(' verbosity: %j', program.verbose);
console.log(' args: %j', program.args);

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