Jemima

A naïve little (puddle) duck typing library for Node.js

Installation

Just install with npm install jemima or add it to your package.json.

If you use a bundler like Browserify, then Jemima will work just fine in-browser too.

Usage

You can use Jemima with JavaScript or CoffeeScript:

var jemima = require('jemima');

jemima = require 'jemima'

Jemima exposes a few functions to help duck-type:

jemima.hasProperty

This function tests to see whether an object has the specified property. You call it with an object (what we're testing) and a string (the property we're testing for); it will return a boolean value indicating whether the object has the property:

var obj = {
    foo: 123
};
 
jemima.hasProperty(obj, 'foo'); // true
jemima.hasProperty(obj, 'bar'); // false

jemima.hasProperties

This function tests to see whether an object has the specified properties. You call it with an object (what we're testing) and an array of strings (the properties we're testing for); it will return a boolean value indicating whether the object has all of the properties:

var obj = {
    foo: 123,
    bar: 456
};
 
jemima.hasProperties(obj, ['foo', 'bar']); // true
jemima.hasProperties(obj, ['foo', 'baz']); // false

jemima.hasMethod

This function tests to see whether an object has the specified method – it's similar to hasProperty but also tests that the property is a function. You call it with an object (what we're testing) and a string (the method we're testing for); it will return a boolean value indicating whether the object has the method:

var obj = {
    foo: function () {},
    bar: 123
};
 
jemima.hasMethod(obj, 'foo'); // true
jemima.hasMethod(obj, 'bar'); // false

jemima.hasMethods

This function tests to see whether an object has the specified methods – it's similar to hasProperties but also tests that the properties are functions. You call it with an object (what we're testing) and an array of strings (the methods we're testing for); it will return a boolean value indicating whether the object has all of the methods:

var obj = {
    foo: function () {},
    bar: function () {},
    baz: 123
};
 
jemima.hasMethods(obj, ['foo', 'bar']); // true
jemima.hasMethods(obj, ['foo', 'baz']); // false

jemima.matches

This function tests whether an object has the specified properties and that the type of object stored in each property is as expected. You call it with an object (what we're testing) and a 'duck' (an object which specifies the expected properties and types); it will return a boolean value indicating whether all of the properties match:

var duck = {
    foo: 'string',
    bar: 'function'
};
 
jemima.matches({
    foo: 'bar',
    bar: function () {}
}, duck); // true
 
jemima.matches({
    foo: 'bar'
}, duck); // false
 
jemima.matches({
    foo: 'bar',
    bar: 'baz'
}, duck); // false

Development

In order to develop Jemima, you'll need to install the following npm modules globally like so:

npm install -g coffee-script
npm install -g jake

And then install development dependencies locally with:

npm install

Once you have these dependencies, you will be able to run the following commands:

jake build: Build JavaScript from the CoffeeScript source.

jake lint: Run CoffeeLint on the CoffeeScript source.

jake test: Run all unit tests.

License

Dual licensed under the MIT or GPL Version 2 licenses.