feature-detect

Feature detection

This library is meant to provide feature detection support for Node.js or Io.js compatible environments. It is not intended to provide feature detection support in browser environments, for which there already are numerous alternatives.

Usage

npm install --save feature-detect

Install time detection (recommended)

To detect features at install time, put an install script similar to the following in package.json:

{ scripts:
  { "install": "feature-detect generators" }
}

In the example above, the feature-detect executable will load the module generators. The module is expected to export a list of tests, like so:

exports.feature = 'Generators'
 
exports.tests =
[ 'generator syntax'
  , function() {
      return function *() { yield true }
    }
  ]
]

When running npm install in an environment that supports generators, nothing will happen, but if generators aren't supported, the installation will fail and you should see output like the following:

WeakMap is not supported in this environment
├ ✘ basic functionality WeakMap is not defined
├ ✘ constructor arguments WeakMap is not defined
├ ✘ WeakMap.prototype.set returns this WeakMap is not defined
├ ✘ WeakMap.prototype.delete WeakMap is not defined
└ ✘ Support frozen objects as keys WeakMap is not defined

Runtime detection

While installation time detection is recommended, it is possible to do runtime detection:

var detect = require('feature-detect')
 
var result = detect(
  { feature: 'WeakMap'
  , tests:
    [ [ 'basic functionality', function() {
        var key = {};
        var weakmap = new WeakMap();
        weakmap.set(key, 123);
        return weakmap.has(key) && weakmap.get(key) === 123;
      } ]
    ]
  }
)
 
result.success? console.log('WeakMap supported!') : console.error('No WeakMap!')

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License: MIT