Clean optional parameters using destructuring

destructured-parameters.js

function fn(mandatoryParameter, {
		optionalA = 'a value',
		optionalB = 'another value',
		optionalC = 'notice that this is using destructured assignment syntax, not object literal syntax'
	} = {} /* unfortunately, we need to specify an empty object default if the consumer provides no object argument */){
	
	// Configuration
	this.configurationPropertyNamespace = { 
		optionalA,
		hardCodedConfig: 'we can use the object literal "default" property naming trick to be more terse'
	}

	// State
	Object.assign(this, { optionalB, optionalC }) // Quickly bind multiple constructor parameters straight onto the instance

	// ...and now, because we used destructuring in the parameters, there is no "options" catch-all object in this 
	// constructor scope that we need to preface our parameters with - all the benefits of providing an object as an
	// argument to a function, with none of the annoying verbosity of unpacking that object!
	console.debug(optionalA, optionalB, optionalC) 
}

// To call this function, we provide a "options" object as an argument as normal.
fn('a name', {
	optionalA: 'a more specific value',
	optionalB: 2,
	optionalC: new Date()
})

// Here's that technique again as tersely as possible:
let newFn = ({
	prop = 'a value'
}={}) => prop

// This is more verbose than using traditional, array-position-based parameters, but the benefit is that you never have to remember the (often quite arbitrary) parameter order of a function in order to use it.

God I love the QOL improvements of ES6/7 so much