have

[stdarg]

a nice arg checking module

[hemanth]

Nice suggestion, noted down. It's a good competition for nopt

[stdarg]

Not exactly. nopt is about command line arguments where have is to validate function arguments. A lot of bugs come down to passing the wrong type of argument and have is useful for validation.

[hemanth]

Yup.

[hemanth]

@stdarg I was pawing at it:

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

In the above method is there way to say which method it was validating the arguments for?

Say like 'WARN: assertion failed for ' + method + ' : ' + message ?

[stdarg]

It's implicit. The general use case of have is to check arguments for a function, e.g.:

/**
 * Config provides a simple read-only API to a configuration object.
 * @param {String} pathToConfigFile The configuration file
 * @param {String} [region] Optional indicator for the current region, e.g. 'en'
 */
function Config(pathToConfigFileIn, region) {
    have(arguments, {pathToConfigFile: 'str', region: 'opt str' });
    [...]
}

In the above example, have would throw if pathToConfigFile is not a string or if region is defined and is not a string. Also, rather than throw, have can do some user defined behavior. The thrown error would have a call stack. If you generated your own have response, you can get the call stack with the following statement:

var stack = new Error().stack;

Though in the above case, we check the arguments object, it could be used to check any object. Another good use would be to validate documents returned from MongoDB or the JSON body of an HTTP request.

I find it a super-handy module.

[hemanth]

Was having the discussion with author and he suggested something similar

[hemanth]

Fixed in http://nmotw.in/have thanks!