Compare array objects to equality

Question

I am searching for a function which compare how much values match in an array. It should be sequence dependent. That mean i.e. the first object in the first array should be compared to equality to the first object in the second array and so on. I actually looked at this, but there become only the length compared and the length is in my case always the same. The possibly objects in the array are 1,2,3,4,5,6,7,8,9. Should I split the arrays and compare them then and when yes how?

Here are two examples:

var array1 = ["3","4","2"];
var array2 = ["9","4","7"];
// result = 1

second example:

var array1 = ["9","4","7","3"];
var array2 = ["3","4","7","2"];
// result = 2

Do it the same way as You do it as a human - go element by element in both arrays and compare them. Where is the problem? — Roman Hocke, Nov 09 '15 at 10:42
`array1.filter(function(v, i) {return v === array2[i];}).length;` — fuyushimoya, Nov 09 '15 at 10:43

score 5 · Accepted Answer · answered Nov 09 '15 at 10:43

Try this

var array1 = ["3","4","2"];
var array2 = ["9","4","7"];

function equal(array1, array2) {
  var len = array1.length, i, count = 0;
  
  for (i = 0; i < len; i++) {
    if (array1[i] === array2[i]) {
      count++;
    }
  }
  
  return count;
}

console.log(equal(array1, array2));

score 0 · Answer 2 · answered Nov 09 '15 at 10:52

Solution which iterates over the items and count the equal elements.

function compare(a1, a2) {
    var i = 0, count = 0;
    while (i < a1.length && i < a2.length) {
        a1[i] === a2[i] && count++;
        i++;
    }
    return count;
}

document.write(compare(["3", "4", "2"], ["9", "4", "7"]) + '<br>');
document.write(compare(["9", "4", "7", "3"], ["3", "4", "7", "2"]) + '<br>');

Compare array objects to equality

2 Answers2