LazyPromise is a cachey promise creator that returns a function. It's good for lazily running things only once.

LazyPromise.js

/*

	LazyPromise is a cachey promise creator that returns a function.

	It's good for lazily running things only once.

	Promise creation is deferred until the first call.

	Construct using same signature as a regular Promise (except it doesn't require `new`).
		
	var lazyp = LazyPromise((resolve, reject) => {})

	The first invocation will create the Promise and run the resolver method.

	lazyp()

	Subsequent invocations will return the cached Promise. 

	lazyp()
	lazyp()

*/

function _LazyPromise(resolver){
	var _promise
	var runner = (resolve, reject) => {
		if(!_promise){
			_promise = new Promise((resolve, reject) => {
				resolver(resolve, reject)
			})
		}
		return _promise
	}
	return runner
}

function LazyPromise(resolver){
	return new _LazyPromise(resolver)
}

module.exports = LazyPromise