add getCommands API for all registered commands

[rawbin-]

var allCommands = yargs.getCommands();
if(allCommands.indexOf(argv[0]) === -1){
    yargs.showHelp();
}

[bcoe]

@rawbin- once we address #853, you should be able to use .strict() to get the behavior you've outlined above.

however, I do like the idea of adding a method for getting all known commands (could see this being handy for some CLIs).

[rawbin-]

this seems not work, do I get something in wrong way?

I just want when I run with cmd pack cmd min,it goes as is, and when I run with cmd xxx it show the help,just as the commented code do

var yargsObj = require('yargs');
var allCommands = ['pack'];
var globalArgv = yargsObj.strict()
    .usage('Usage: $0 <command> [options]')
    .command('pack', 'pack the code', function (yargs) {
        console.log('hit pack cmd')
    })
    .command('min', 'min the code', function (yargs) {
        console.log('hit min cmd')
    })
    .help('h').alias('h', 'help')
    .argv;

console.log(globalArgv._)

// if (globalArgv._.length === 0 || allCommands.indexOf(globalArgv._[0]) === -1) {
//     yargsObj.showHelp();
// }