check-types.js

A tiny JavaScript library for checking types and throwing exceptions.

Why would I want such a thing?

Writing explicit conditions in your functions for checking arguments and throwing exceptions is a task that swiftly becomes tiresome and adds complexity to your codebase.

The purpose of check-types.js is to remove this burden from JavaScript application developers in an efficient and robust manner.

How tiny is it?

14.3 kb unminified with comments, 2.2 kb minified, 0.8 kb minified + gzipped.

How do I install it?

Any of the following will do:

npm install check-types

jam install check-types

bower install check-types

component install philbooth/check-types.js

git clone git@github.com:philbooth/check-types.js.git

How do I use it?

If you are running in Node.js, Browserify or another CommonJS-style environment, you can require check-types.js like so:

var check = require('check-types');

It also the supports the AMD-style format preferred by Require.js:

require.config({
    paths: {
        check: 'check-types.js/src/check-types'
    }
});

require([ 'check' ], function (check) {
});

If you are including check-types.js with an HTML <script> tag, or neither of the above environments are detected, check-types.js will just export its interface globally as check.

Once you have loaded the library in your application, a whole bunch of functions are available to call:

• check.quacksLike(thing, duck): Tests whether an object 'quacks like a duck'. Returns true if the first argument has all of the properties of the second, archetypal argument (the 'duck'). Returns false otherwise. If either argument is not an object, an exception is thrown.

• check.verifyQuack(thing, duck, message): Throws an exception if an object does not 'quack like a duck'.

• check.isInstance(thing, prototype): Returns true if an object is an instance of a prototype, false otherwise.

• check.verifyInstance(thing, prototype, message): Throws an exception if an object is not an instance of a prototype.

• check.isEmptyObject(thing): Returns true if something is an empty, non-null, non-array object, false otherwise.

• check.verifyEmptyObject(thing, message): Throws an exception unless something is an empty, non-null, non-array object.

• check.isObject(thing): Returns true if something is a non-null, non-array, non-date object, false otherwise.

• check.verifyObject(thing, message): Throws an exception unless something is a non-null, non-array, non-date object.

• check.isLength(thing, length): Returns true if something has a length property that matches the specified length, false otherwise.

• check.verifyLength(thing, length, message): Throws an exception unless something has a length property matching the specified length.

• check.isArray(thing): Returns true something is an array, false otherwise.

• check.verifyArray(thing, message): Throws an exception unless something is an array.

• check.isDate(thing): Returns true something is a date, false otherwise.

• check.verifyDate(thing, message): Throws an exception unless something is a date.

• check.isFunction(thing): Returns true if something is function, false otherwise.

• check.verifyFunction(thing, message): Throws an exception unless something is function.

• check.isUnemptyString(thing): Returns true if something is a non-empty string, false otherwise.

• check.verifyUnemptyString(thing, message): Throws an exception unless something is a non-empty string.

• check.isString(thing): Returns true if something is a string, false otherwise.

• check.verifyString(thing, message): Throws an exception unless something is a string.

• check.isPositiveNumber(thing): Returns true if something is a number greater than zero, false otherwise.

• check.verifyPositiveNumber(thing, message): Throws an exception unless something is a number greater than zero.

• check.isNegativeNumber(thing): Returns true if something is a number less than zero, false otherwise.

• check.verifyNegativeNumber(thing, message): Throws an exception unless something is a number less than zero.

• check.isEvenNumber(thing): Returns true if something is an even number, false otherwise.

• check.verifyEvenNumber(thing, message): Throws an exception unless something is an even number.

• check.isOddNumber(thing): Returns true if something is an even number, false otherwise.

• check.verifyOddNumberthing, message): Throws an exception unless something is an even number.

• check.isNumber(thing): Returns true if something is a number, false otherwise. In this case, NaN is not considered a number.

• check.verifyNumber(thing, message): Throws an exception unless something is a number. In this case, NaN is not considered a number.

How do I set up the build environment?

The build environment relies on Node.js, NPM, Jake, JSHint, Mocha, Chai and UglifyJS. Assuming that you already have Node.js and NPM set up, you just need to run npm install to install all of the dependencies as listed in package.json.

The unit tests are in test/check-types.js. You can run them with the command npm test or jake test. To run the tests in a web browser, open test/check-types.html.