How to get distinct values from an array of objects in JavaScript?

Question

Assuming I have the following:

var array = 
    [
        {\"name\":\"Joe\", \"age\":17}, 
        {\"name\":\"Bob\", \"age\":17}, 
        {\"name\":\"Carl\         


        

Answer 1

Here's another way to solve this:

var result = {};
for(var i in array) {
    result[array[i].age] = null;
}
result = Object.keys(result);

I have no idea how fast this solution is compared to the others, but I like the cleaner look. ;-)

---

EDIT: Okay, the above seems to be the slowest solution of all here.

I've created a performance test case here: http://jsperf.com/distinct-values-from-array

Instead of testing for the ages (Integers), I chose to compare the names (Strings).

Method 1 (TS's solution) is very fast. Interestingly enough, Method 7 outperforms all other solutions, here I just got rid of .indexOf() and used a "manual" implementation of it, avoiding looped function calling:

var result = [];
loop1: for (var i = 0; i < array.length; i++) {
    var name = array[i].name;
    for (var i2 = 0; i2 < result.length; i2++) {
        if (result[i2] == name) {
            continue loop1;
        }
    }
    result.push(name);
}

The difference in performance using Safari & Firefox is amazing, and it seems like Chrome does the best job on optimization.

I'm not exactly sure why the above snippets is so fast compared to the others, maybe someone wiser than me has an answer. ;-)