@cycxllin/cmpt315-a2/isArrayFactorChain.js

Fulfills CMPT 315 Assignment 2, MacEwan University Winter 2024.

/*
Return true or false if an array is a factor chain or not.
Parameters: array of numbers
Returns: bool
    -1 if error
*/

function isArrayFactorChain(arr){
    if (Array.isArray(arr)){
        let notNumError = "Error: All elements on array must be type: number";

        if (arr.length > 1){
            let prev = arr[0];
            //check if prev is type number
            if (typeof prev != 'number'){
                console.error(notNumError);
                return -1;
            }

            // determine if the next number on array is a factor of the previous
            for (let i=1; i<arr.length; i++){
                let next = arr[i];
                //check if next is type number
                if (typeof next != 'number'){
                    console.error(notNumError);
                    return -1;
                }

                if (next % prev == 0){
                    //next is a factor of the previous number so move on
                    prev = next;
                    continue;
                } else {
                    // not a factor of prev so stop and return false
                    return false;
                }
            }

            //reached end of array and all are factors of previous
            return true;

        } else { //there is nothing to compare to the first value
            console.error("Error: Array must have at least 2 elements");
            return -1;
        }
    } else {
        console.error("Error: Parameter passed is not an array");
        return -1;
    }
}

module.exports = isArrayFactorChain;