How to compare to different arrays in javascript/jquery and get back the columns with difference in an array

Question

Since I don't know how this works very well and other questions such as: How to compare arrays in JavaScript? or, JavaScript array difference are completely different questions and after 1 and a half hours of scouring the web no results I am going to go and ask this question simply. Say you have two arrays [1,2,3] and [1,4,1]. Then how would you get a program to make our variable (say x) to be [1,2] (because column 1 and 2 are different if you count the first column as column 0)?

Answer 1

Please see this:

var array1 = [1, 2, 3];
var array2 = [1, 4, 1];

var columndiff = [];

for (i = 0; i < array1.length; i++) {
  if (array1[i] != array2[i]) 
    columndiff.push(i);
}

console.log(columndiff);

Note: Here we are assuming that array1 and array2 has equal length

Answer 2

ES2015 code:

const a = [1, 2, 3];
const b = [1, 4, 1];

const result = a.reduce((res, val, index) => { 
    if (val !== b[index]) res.push(index);
    return res;
}, []);

console.log(result); // [1, 2]

Answer 3

You can simply do like this;

var arr = [1,3,4,5,2,3],
    brr = [1,3,5,5,1,2],
    res = arr.reduce((p,c,i) => c !== brr[i] ? p.concat(i) : p,[]);
console.log(res);