nodejs command line parameter processing module commander usage example_node.js

It is true that the built-in process.agrv was used for processing before. This can work, but it is not easy to use, so the great master tj wrote one, my god, which is completely superior:

1. Installation

Copy code The code is as follows:

npm install commander

2. Option analysis

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.

Copy code The code is as follows:

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var program = require('commander');

program
.version('0.0.1')
.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')
.parse(process.argv);

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. Multi-word options such as “–template-engine” are camel-cased, becoming program.templateEngine etc.

3. Automatically generate help information

Copy code The code is as follows:

$ ./examples/pizza --help

Usage: pizza [options]

Options:

-V, --version output the version number
-p, --peppers Add peppers
-P, --pineapple Add pineapple
-b, --bbq Add bbq sauce
-c, --cheese Add the specified type of cheese [marble]
-h, --help output usage information

Of course you can also generate it manually:

Copy code The code is as follows:

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var program = require('../');

function list(val) {
Return val.split(',').map(Number);
}

program
.version('0.0.1')
.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('');
console.log(' $ custom-help --help');
console.log(' $ custom-help -h');
console.log('');
});

program.parse(process.argv);

console.log('stuff');

4. Give a complete example

Copy code The code is as follows:

function range(val) {
  return val.split('..').map(Number);
}
 
function list(val) {
  return val.split(',');
}
 
function collect(val, memo) {
  memo.push(val);
  return memo;
}
 
function increaseVerbosity(v, total) {
  return total 1;
}
 
program
  .version('0.0.1')
  .usage('[options] ')
  .option('-i, --integer ', 'An integer argument', parseInt)
  .option('-f, --float ', 'A float argument', parseFloat)
  .option('-r, --range ..', 'A range', range)
  .option('-l, --list ', '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)
  .parse(process.argv);
 
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);