Creating an array consisting of the largest values of each sub-array does not work as expected

Question

Find the largest number in each of the sub-array and then make an array of those largest numbers.[[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1

Answer 1

Potentially simpler method to achieve same result - simplicity is prerequisite for reliability...

function largestOfFour(arr){
    // assumes compatible browser, or shim: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/map#Browser_compatibility
    // map array each element into new value based on callback's return
    return arr.map(function(subarr){
        // sort to get highest value at front, and then return it
        return subarr.sort(function(a,b){
            return b-a;
        })[0];
    });
}

---

or with Math.max (see comments...)

function largestOfFour(arr){
    // assumes compatible browser, or shim: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/map#Browser_compatibility
    // map array each element into new value based on callback's return
    return arr.map(function(subarr){
        // sort to get highest value at front, and then return it
        return Math.max.apply(null, subarr);
    });
}