Lazy

An tiny, isomorphic, lazy value initialization library. This library wraps a value factory with a lazy object that will deffer factory execution until the value is actually used. Afterwards, the value is cached and is immediately available.

Installation

npm install @rstone770/lazy --save

Example

var lazy = require('@mosfetish/lazy');

var lazied = lazy(function () {
  var fib = function(n) {
    return n <= 2
      ? 1
      : fib(n - 1) + fib(n - 2);
  };

  return fib(10);
});

// now use.
var fib10 = lazied.value;

Api

(factory)

Return: Lazy: ({created: boolean, value: any})

Calling the api directly will wrap a factory function and return a lazy instance. The lazy instance has two properties; value and created.

Lazy.created

This value is initially false and will become true after the factory has been invoked.

var lazied = lazy(function() { /*...*/ });
lazied.created; // false

var value = lazied.value;
lazied.created; // true

Lazy.value

This is the actual value that the factory returns. Initially it is null, but when accessed will be assigned to the result of the factory. This value is cached so future calls get this value immediately.

var lazied = lazy(function() { return {} });
lazied.value === lazied.value; // true

isLazy(value)

Return: Boolean Determines if the value is a lazy object.

lazy.isLazy({}); // false
lazy.isLazy(); // false
lazy.isLazy('string'); // false
lazy.isLazy(lazy(function() {})); // true

version

The current library version.

##License Lazy is licensed under MIT.