Extracting the most duplicate value from an array in JavaScript (with jQuery)

Question

I have several array to deal with. I need to extract the most duplicate value from each array.

From [3, 7, 7, 7], I need to find the value 7

Answer 1

Here's a simpler and faster version using only JavaScript:

var arr = [3, 7, 7, 7, 10, 10, 8, 5, 5, 5, 5, 20, 20, 1];
var counts = {}, max = 0, res;
for (var v in arr) {
  counts[arr[v]] = (counts[arr[v]] || 0) + 1;
  if (counts[arr[v]] > max) { 
    max = counts[arr[v]];
    res = arr[v];
  }
}
alert(res + " occurs " + counts[res] + " times");

Note that this is a much more efficient since you're looping over the data once, if you're sorting very large arrays this will start to matter.