あなたが探しているものを100%確信しているわけではありませんが、これだと思います.
// Original data
var choices = [
"choice 1",
"choice 1",
"choice 2",
"choice 3",
"choice 3",
"choice 3",
"choice 3",
"choice 3",
"choice 3",
"choice 4",
"choice 4",
"choice 4"];
//Create the results array
var result = new Object();
for (var choice in choices) {
if (result[choices[choice]] === undefined)
result[choices[choice]] = 1;
else
result[choices[choice]]++;
}
//Print result
var str = "";
for (var item in result)
str += item + ": " + result[item] + "<br />";
document.getElementById("resultDiv").innerHTML = str;
出力:
choice 1: 2
choice 2: 1
choice 3: 6
choice 4: 3