HAVE.js

Have your arguments, and validate it too:

var have = require('have');

function safeFunc(id, options, callback) {
  have(arguments,
    { id       : 'string or number'
    , options  : 'optional object'
    , callback : 'function'
    });
}

HAVE.js gives you a mini-DSL to quickly validate your function arguments.

MINI-DSL

In order of precedence:

• opt X|optional X - Optional X
• X or Y - Either X or Y
• X a|X arr|x array - Array of X
• s|str|string - String
• n|num|number - Number
• b|bool|boolean - Boolean
• f|fun|func|function - Function
• a|arr|array - Array
• o|obj|object - Object
• r|rx|regex|regexp - RegExp
• d|date - Date

These matchers can be combined. These are all valid HAVE.js matchers:

• str or num array - String or Array of Number
• num arr or str arr - Array of Number or Array of String
• num a a a a - Array of Array of Array of Array of Number
• opt str or num array - Optional (String or Array of Number)

Have fun!

PARSED ARGUMENTS

The HAVE.js function also returns any parsed argument collected in a hash keyed to the same key as was given in the schema. You can inspect the returned object to more easily obtain the parsed value without having to duplicate the HAVE.js parsing logic in your code to extract them.

var have = require('have');

function safeFunc(id, options, callback) {
  var args = have(arguments,
    { id       : 'string or number'
    , options  : 'optional object'
    , callback : 'function'
    });
  
  options = args.options || { some: 'value' };
  
  // some stuff
  someDb.loadById(args.id, options, args.callback);
};

For a more careful argument names parsing you can pass several schema.

var have = require('have');

function safeFunc() {
  var args = have(arguments,
    [ { id       : 'string or number'
      , options  : 'optional object'
      , callback : 'function'
      }
    , { query    : 'object'
      , options  : 'optional object'
      , callback : 'function'
      }
    ]);
  
  var options = args.options || { some: 'value' };
  
  // some stuff
  if (args.id) {
    someDb.loadById(args.id, options, args.callback);
  } else {
    someDb.find(args.query, options, args.callback);    
  }
};

Use "strict" mode to fail for those extra arguments that do not match the schema.

var have = require('have');

function safeFunc(id, options, callback) {
  var args = have.strict(arguments,
    { id       : 'string or number'
    , options  : 'optional object'
    , callback : 'function'
    });
  
  // some stuff
};

// This throws an AssertionError: Wrong argument "foo"
safeFunc('id', { key: 'value' }, cb, 'foo') 

And, of course, you can define your own matchers and override built-in.

var have = require('have').with(
  { 'MyClass|mycls': function (myClass) {
    return myClass instanceof MyClass
  }
  , 's|str|string': function (str) {
      return typeof str === 'string' && str.length
    } 
  });

function safeFunc(myClass, msg) {
  have(arguments,
    { myClass : 'MyClass'
    , msg     : 'optional string'
    });
  
  // some stuff
};

// This throws an AssertionError: myClass argument is not MyClass
safeFunc({}, 'hello') 

SOFT ASSERTS

If you are like me and you write a lot of method preconditions that should be turned off or atleast, should not throws in production, you can replace HAVE.js assert function like so:

var have = require('have');

have.assert(function(cond, message) {
  if (!cond) {
    console.log('WARN: assertion failed: ' + message);
  }
});

This will replace the assert function HAVE.js uses internally with your implementation so if you want to completely turns assertion off, then just give it a no-op function.

SHORTERs

For those who like it short, the above example can also be written like this:

var have = require('have');

function safeFunc(id, options, callback) {
  have(arguments, { id: 's or n', options: 'opt o', callback: 'f' });
}

This is not very readable, of course. But HAVE.js does not dictate your readability preference for you. So go wild if you think it is ok : )

LICENSE

BSD (if you don't like BSD, just contact me)

CHANGELOG

v0.4.0

• Add support for custom arguments matchers

v0.3.0

• The function now returns parsed arguments as a hash object.

v0.2.3

• Adds the forgotten boolean support.

v0.2.1 - v0.2.2

• Eat null and undefined where optional argument is expected.

SUPPORT / CONTRIBUTE

Test with npm test or make test.

Just open a new GitHub issue or ping me @chakrit on Twitter.

Pull requests and feature suggestions totally welcome.

    40	Chakrit Wichian
     3	Makeev Vitaliy
     1	Edmond Meinfelder