conforms

Usage:

var conforms = require('conforms');

conforms(actual, expected);

where actual is the value to validate, and expected is an "interface" template describing the required properties and types. Throws an exception if non-conformant, otherwise returns true. This can be used to implement duck typing, for example:

var duck = { 
  quack: function(volume) {}, 
};

var obj = {quack: function(volume) { console.log('quack'); }};

conforms(obj, duck); // returns true

obj is considered to conform to the duck interface because it has all of the required properties: quack in this case is a method, with the appropriate parameter names (volume, but extra parameters can exist without violating conformance). If another object is passed without meeting these requirements, conforms() will throw an exception.

Interface specifications

The interface template (expected) is an actual value, not a type name, but only the salient typing information is compared. This includes:

• The JavaScript type (usingtypeof)
• Integer/non-integer numbers (using Number.isInteger)
• Array/non-array objects (using Array.isArray)
• Recursing into (non-array) objects and checking conformance of each property (extra properties are allowed)
• Matching the function parameter names (names must be equal, but extra parameters are allowed)

For more examples, see test.js.

License

MIT