randSplit.js

module.exports = randSplit;

function randSplit(_ary, _percentageSplit) {

	// make sure the params are arrays
	if(!Array.isArray(_ary) || !Array.isArray(_percentageSplit)) {
		console.log(`Both arguments must be of array type`);
		return false;
	}

	// indeed, logicaly this sum of percentage split should be 100
	if(_percentageSplit.reduce((a, b) => a + b, 0) != 100) {
		console.log(`Sum of elements of _percentageSplit must be 100, but is `,_percentageSplit.reduce((a, b) => a + b, 0).toString());
		return false;
	}

	// because we don't want to modify the original array
	_ary = JSON.parse(JSON.stringify(_ary));

	// we will populate result object for response
	let result = {};
	
  let eleSplit = []
  for (let i in _percentageSplit) {
		let eleInThisAry = parseInt(_ary.length*_percentageSplit[i]/100);
    console.log(`${eleInThisAry.toString()} (${_percentageSplit[i]}% of ${_ary.length}) elements in ${i} object`);
    eleSplit.push(eleInThisAry);
	}

	for (let i in _percentageSplit) {
		result[i] = [];
		
		while(result[i].length != eleSplit[i]){
			result[i].push(_ary.splice(Math.floor(Math.random()*_ary.length), 1)[0])
		}
	}

	return result
};


/* TEST */
/*
let res1 = randSplit([1,2,3,4,5,6,7,8,9,10], [20,30,5]);
// should return false : sum of 2nd argument is not 100
console.log("res1:: ", res1);

let res2 = randSplit("[1,2,3,4,5,6,7,8,9,10]", [20,30,50]);
// should return false : first argument is not an array
console.log("res2:: ", res2);

let res3 = randSplit([1,2,3,4,5,6,7,8,9,10], [20,30,50]);
// should return proper response
console.log("res3:: ", res3);
*/