Small snippet of useful code

gistfile1.js

var cases, delegator;

// Example returns for illustration only.
cases = {
  alpha: function() {
    // statements
    // a return
    return [ "Alpha", arguments.length ];
  },
  beta: function() {
    // statements
    // a return
    return [ "Beta", arguments.length ];
  },
  _default: function() {
    // statements
    // a return
    return [ "Default", arguments.length ];
  }
};

delegator = function() {
  var args, key, delegate;

  // Transform arguments list into an array
  args = [].slice.call( arguments );

  // shift the case key from the arguments
  key = args.shift();

  // Assign the default case handler
  delegate = cases._default;

  // Derive the method to delegate operation to
  if ( cases.hasOwnProperty( key ) ) {
    delegate = cases[ key ];
  }

  // The scope arg could be set to something specific,
  // in this case, |null| will suffice
  return delegate.apply( null, args );
};

// 7.A.1.3
// Put the API in 7.A.1.2 to work:

delegator( "alpha", 1, 2, 3, 4, 5 );
// [ "Alpha", 5 ]

// Of course, the `case` key argument could easily be based
// on some other arbitrary condition.

var caseKey, someUserInput;

// Possibly some kind of form input?
someUserInput = 9;

if ( someUserInput > 10 ) {
  caseKey = "alpha";
} else {
  caseKey = "beta";
}

// or...

caseKey = someUserInput > 10 ? "alpha" : "beta";

// And then...

delegator( caseKey, someUserInput );
// [ "Beta", 1 ]

// And of course...

delegator();
// [ "Default", 0 ]


From https://github.com/rwaldron/idiomatic.js/