Getting max value(s) in JSON array

Just cycle through the array, and keep track of the max as you go:

function getMax(arr, prop) {
    var max;
    for (var i=0 ; i<arr.length ; i++) {
        if (max == null || parseInt(arr[i][prop]) > parseInt(max[prop]))
            max = arr[i];
    }
    return max;
}

Usage is like:

var maxPpg = getMax(arr, "ppg");
console.log(maxPpg.player + " - " + maxPpg.team);

Fiddle demo

Edit

You can also use the Javascript "sort" method to get the top n values:

function getTopN(arr, prop, n) {
    // clone before sorting, to preserve the original array
    var clone = arr.slice(0); 

    // sort descending
    clone.sort(function(x, y) {
        if (x[prop] == y[prop]) return 0;
        else if (parseInt(x[prop]) < parseInt(y[prop])) return 1;
        else return -1;
    });

    return clone.slice(0, n || 1);
}

Usage:

var topScorers = getTopN(arr, "ppg", 2);
topScorers.forEach(function(item, index) {
    console.log("#" + (index+1) + ": " + item.player);
});

Fiddle demo

I found the following approach very neat:

arr.sort( 
  function(a, b) {
     return parseFloat(b['ppg']) - parseFloat(a['ppg']);
  }
)[0]['player']

Demo in snippet:

var arr =[
{
    "player" : "Andre Drummond",
    "team" : "Detroit Pistons",
    "ppg" : "15.4",
    "rpg" : "11.6",
    "apg" : "2.4",
    "bpg" : "1.6",
    "spg" : "0.8",
    "3pg" : "0.1"
},
{
    "player" : "Anthony Davis",
    "team" : "New Orleans Pelicans",
    "ppg" : "16.4",
    "rpg" : "13.6",
    "apg" : "2.6",
    "bpg" : "3.5",
    "spg" : "1.2",
    "3pg" : "0.1"
},
{
    "player" : "Carmelo Anthony",
    "team" : "New York Knicks",
    "ppg" : "27.4",
    "rpg" : "5.4",
    "apg" : "4.5",
    "bpg" : "1.1",
    "spg" : "1.5",
    "3pg" : "1.6"
}
]
console.log(
arr.sort( 
    function(a, b) {
       return parseFloat(b['ppg']) - parseFloat(a['ppg']);
    }
    )[0]['player']
);

First, I sort the array in descending order, then I choose the first element which contains the max value. In the code, I found the player who has the max ppg value. Hope this helps!

This should work:

var highestValue = 0; //keep track of highest value

//loop through array of objects
for (var i=0, len = ary.length; i<len; i++) {
  var value = Number(ary[i]["ppg"]);
  if (value > highestValue) {
      highestValue = value;
  }
}