Question

I have a function which job is to get a total from values from an array, however it doesn’t work. EG. my array looks like

    [["10", "", ""], ["10", "", ""], ["10", "", ""]]

So the value i am expecting is 30 however i am getting 0101010 in console.log

function createAv(results){
    var av = results;

    var a1 = 0;
    var a2 = 0;
    var a3 = 0;

    function percentage(av){
    var n1 = 0;
    for (var index = 0; index < av.length; index++) {

            n1 += av[index][0];
        a1 = (av[0][0] / n1) * 100; 
        a2 = (av[1][0] / n1) * 100; 
        a3 = (av[2][0] / n1) * 100; 
    }
      return n1;
    }

    var test = (percentage(av));

    return test;

  }

Answer 1

It’s because the numbers are in strings. You can add strings to other strings (and even add numerical values to those strings), but you’ll end up with a concatenated string.

If they need to be strings, that’s OK – you can use parseInt() to treat them like numbers.

for (var index = 0; index < av.length; index++) {

    n1 += parseInt(av[index][0], 10);

    a1 = (parseInt(av[0][0], 10) / n1) * 100; 
    a2 = (parseInt(av[1][0], 10) / n1) * 100; 
    a3 = (parseInt(av[2][0], 10) / n1) * 100; 
}