firedrawndagger firedrawndagger - 3 months ago 20
Javascript Question

Compare JavaScript Array of Objects to Get Min / Max

I have an array of objects and I want to compare those objects on a specific object property. Here's my array:

var myArray = [
{"ID": 1, "Cost": 200},
{"ID": 2, "Cost": 1000},
{"ID": 3, "Cost": 50},
{"ID": 4, "Cost": 500}
]


I'd like to zero in on the "cost" specifically and a get a min and maximum value. I realize I can just grab the cost values and push them off into a javascript array and then run the Fast JavaScript Max/Min.

However is there an easier way to do this by bypassing the array step in the middle and going off the objects properties (in this case "Cost") directly?

Answer

The fastest way, in this case, is looping through all elements, and compare it to the highest/lowest value, so far.

(Creating an array, invoking array methods is overkill for this simple operation).

 // There's no real number bigger than plus Infinity
var lowest = Number.POSITIVE_INFINITY;
var highest = Number.NEGATIVE_INFINITY;
var tmp;
for (var i=myArray.length-1; i>=0; i--) {
    tmp = myArray[i].Cost;
    if (tmp < lowest) lowest = tmp;
    if (tmp > highest) highest = tmp;
}
console.log(highest, lowest);