Compare arrays return true/false

compare-arrays.js

//test #1: exactly the same.
let myArrayA = [
	{periodSeqNo: 30010, period_month :'jan 2020', start_date: '2020-01-01', end_date: '2020-01-31', opening_bal: 350000.11, opening_rate: 3.100, int_amount_charged: 255.10},
	{periodSeqNo: 30020, period_month :'feb 2020', start_date: '2020-02-01', end_date: '2020-02-29', opening_bal: 360000.12, opening_rate: 3.200, int_amount_charged: 255.20},
	{periodSeqNo: 30030, period_month :'mar 2020', start_date: '2020-03-01', end_date: '2020-03-31', opening_bal: 370000.13, opening_rate: 3.300, int_amount_charged: 255.30},
];
let myArrayB = [
	{periodSeqNo: 30010, period_month :'jan 2020', start_date: '2020-01-01', end_date: '2020-01-31', opening_bal: 350000.11, opening_rate: 3.100, int_amount_charged: 255.10},
	{periodSeqNo: 30020, period_month :'feb 2020', start_date: '2020-02-01', end_date: '2020-02-29', opening_bal: 360000.12, opening_rate: 3.200, int_amount_charged: 255.20},
	{periodSeqNo: 30030, period_month :'mar 2020', start_date: '2020-03-01', end_date: '2020-03-31', opening_bal: 370000.13, opening_rate: 3.300, int_amount_charged: 255.30},
];

/*
let testFound = myArrayB.find(elt => elt.periodSeqNo === 30020); //return element or undefined;
console.log('found:', testFound); */

//IF Objects are same, returns TRUE; else rtn false;
const shallowCompareFN = (obj1, obj2) =>
    Object.keys(obj1).length === Object.keys(obj2).length && 
        Object.keys(obj1).every(key => obj2.hasOwnProperty(key) && obj1[key] === obj2[key]
);



const compareArraysFN = (arrA, arrB) => {
	//1. are array lengths the same?
	if (arrA.length != arrB.length)
		return false; //exit.. NOT THE SAME, we are done.
	else { //lengths are the same, are objects (by PK periodSeqNo equivalent?
		//pick one array A or B, loop thru it;
		
		//dont use .map for iterations (cannot break/exit early out of loop); map is best used for obtaining a new transformed array.
		let rtnValTF = true;
		for( const item of arrA) {
			//Given ArrayA, look in arrayB for element satisfying a condition (same Key, in this case)
			const foundElt = arrB.find(elt => elt.periodSeqNo === item.periodSeqNo);
			if (foundElt === undefined) {
				return false; //exit.. A+B are different.
			} else {//found, compare objects (i.e. each prop in the objs)
				/*  console.warn( 'objA:', item);
				console.log( 'objB:', foundElt); */
				console.log( 'objB:', foundElt);
				var trueFalse = shallowCompareFN(item, foundElt)
				if (!trueFalse) {
					rtnValTF = false;
					break; //ON FALSE, we are done, early exit, no need to keep looping.
				}
			}
		}
		return rtnValTF;
 	}
}

let tf = compareArraysFN( myArrayA, myArrayB);
console.log('test#1 - are arrays same?:', tf);