keynum

A simple enum type with emphasis on keys

Basic usage

var Enum = require('keynum');

var size = Enum(['SMALL', 'MEDIUM', 'BIG']);

console.log(size.SMALL); // => 0
console.log(size.MEDIUM); // => 1
console.log(size.BIG); // => 2

// using .get
console.log(size.get('SMALL')); // => 0
console.log(size.get(0)); // => 0

// getting all enumerated keys
var keys = size.keys(); // ['SMALL', 'MEDIUM', 'BIG']

keynum is intended to make key:value matching easy using .has and .get

// the key is returned if the given key or value exists
console.log(size.has('SMALL')); // => 'SMALL'
console.log(size.has(0)); // => 'SMALL'

console.log(size.has('TINY')); // => false
console.log(size.get('TINY') && size.get(45)); // => undefined

so you can do things like this:

var validType = size.get(size.has(someKeyOrValue) || size.MEDIUM); // defaults to MEDIUM if an invalid type is given

keynum types are always returned as a frozen object to prevent changes, unless false is given as the freeze option.

More advanced enumeration

An enum can be created from an array or an object. This gives greater control over the associated values. By default values start at 0 and increment by 1 as can be seen earlier. This can be overridden by providing single key:value objects as an array entry:

var size = Enum(['TINY', 'SMALL', {MEDIUM: 4}, {BIG: 10}, 'MASSIVE']);
console.log(size.TINY); // => 0
console.log(size.MEDIUM); // => 4
console.log(size.MASSIVE); // => 11

or by just using an object:

var size = Enum({
    SMALL: 1,
    BIG: 10
    MEDIUM: 5
}); // order does not matter
console.log(size.SMALL); // => 1
console.log(size.MEDIUM); // => 5
console.log(size.BIG); // => 10

The new operator is optional; use however you would like to: Enum(['A', 'B', 'C']) || new Enum(['D', 'E', 'F']);

Options

An enum can now be given options at creation:

var size = Enum(['SMALL', 'MEDIUM', 'BIG'], {
    freeze: false,          // defaults to true
    ignoreCase: true,       // defaults to false
    preserveCase: false     // defaults to true
});

• freeze option will return a frozen object, if true (default)
• ignoreCase will allow case-insensitive matching of keys using has or get, if true
• preserveCase determines how properties are cased and can be any of the following
  • true => preserves keys exactly as given (default)
  • false => converts keys to UPPERCASE
  • 'upper' => same as false
  • 'lower' => converts keys to lowercase

Example

var size = Enum(['sMaLL', 'MEDium', 'BIG'], { preserveCase: 'lower', ignoreCase: true });
console.log(size.small); // => 0
console.log(size.has('sMaLL')) // => 'small'

Dynamic enumerated types

An unfrozen enum can have new enumerations added using the add method:

var size = Enum(['SMALL', 'MEDIUM', 'BIG'], {freeze:false});
size.add('MASSIVE')
    .add('TINY', -1);
console.log(size.MASSIVE); // => 3
console.log(size.TINY); // => -1
console.log(size.keys()) // => [ 'SMALL', 'MEDIUM', 'BIG', 'MASSIVE', 'TINY' ]

If a value is not specified for the key it is incremented from the highest existing value. Keys must still remain unique, and duplicate values will throw an error; i.e. size.add('LITTLE', 0) => Error: The specified value is already enumerated

Tests

Run tests using npm test