Javascript ES6 function with required arguments example

fn-args-required.js

const throwIfMissing = (p) => { throw new Error(`Missing parameter: ${p}`); }

function famTree(dad = throwIfMissing("dad"),mom = throwIfMissing("mom"),...siblings) {
	console.group("Family");
		console.log(`Dad: ${dad}`);
		console.log(`Mom: ${mom}`);
		if(siblings.length > 0) {
			console.log(`Siblings: ${siblings.join()}`);
		}
	console.groupEnd();
}

// call famTree with no arguments
famTree(); // throws first error - Missing paremeter: dad

// call famTree with one argument
famTree("Daddy"); // throws second error - Missing paremeter: mom

//call famTree with at least two arguments and body of function will execute
famTree("Daddy", "Mommy", "Big bro", "Lil sis", "Twin bro");