capability.js - javascript environment capability detection

The capability.js library provides capability detection for different javascript environments.

Documentation

This project is empty yet.

Installation

npm install capability

bower install capability

Environment compatibility

The lib requires only basic javascript features, so it will run in every js environments.

Requirements

If you want to use the lib in browser, you'll need a node module loader, e.g. browserify, webpack, etc...

Usage

In this documentation I used the lib as follows:

var capability = require("capability");

Capabilities API

Defining a capability

You can define a capability by using the define(name, test) function.

capability.define("Object.create", function () {
    return Object.create;
});

The name parameter should contain the identifier of the capability and the test parameter should contain a function, which can detect the capability. If the capability is supported by the environment, then the test() should return true, otherwise it should return false.

You don't have to convert the return value into a Boolean, the library will do that for you, so you won't have memory leaks because of this.

Testing a capability

The test(name) function will return a Boolean about whether the capability is supported by the actual environment.

console.log(capability.test("Object.create"));
    // true - in recent environments
    // false - by pre ES5 environments without Object.create

You can use capability(name) instead of capability.test(name) if you want a short code by optional requirements.

Checking a capability

The check(name) function will throw an Error when the capability is not supported by the actual environment.

capability.check("Object.create");
    // this will throw an Error by pre ES5 environments without Object.create

Checking capability with require and modules

It is possible to check the environments with require() by adding a module, which calls the check(name) function. By the capability definitions in this lib I added such modules by each definition, so you can do for example require("capability/es5"). Ofc. you can do fun stuff if you want, e.g. you can call multiple checks from a single requirements.js file in your lib, etc...

Definitions

Currently the following definitions are supported by the lib:

• strict mode
• arguments.callee.caller
• es5
  • Array.prototype.forEach
  • Array.prototype.map
  • Function.prototype.bind
  • Object.create
  • Object.defineProperties
  • Object.defineProperty
  • Object.prototype.hasOwnProperty
• Error.captureStackTrace
• Error.prototype.stack

License

MIT - 2016 Jánszky László Lajos