Most efficient way to compare multiple arrays based on a fixed element and copy the largest one?-CodePudding

I've four arrays of length 18 (k1,k2,k3&k4). I want to compare the last element of each array & copy the contents of the array with the largest final element.

Currently, this is how I'm doing it:

if (this.k4[17]>=this.k1[17] && this.k4[17]>=this.k2[17] && this.k4[17]>=this.k3[17])
            m = this.k4.filter(() => true);
        else if(this.k1[17]>=this.k4[17] && this.k1[17]>=this.k2[17] && this.k1[17]>=this.k3[17])
            m = this.k1.filter(() => true);
        else if(this.k2[17]>=this.k4[17] && this.k2[17]>=this.k1[17] && this.k2[17]>=this.k3[17])
            m = this.k2.filter(() => true);
        else
            m = this.k3.filter(() => true);

But this isn't scalable incase I added more arrays in the future.

Here is another method:

var maxlast = [this.k1[17],this.k2[17],this.k3[17],this.k4[17]];
var max = maxlast.reduce(function(a,b){return Math.max(a, b)}, -Infinity);
var pos = maxlast.indexOf(max) 1;
m = eval("this.k" pos ".filter(() => true);");

I've heard eval() is a major security risk, is there an alternative approach?

CodePudding user response：

You can use sort and just return the first element of descending sorted list

const arr = [this.k1, this.k2, this.k3, this.k4]
// sort desc
const arrayHasMaxLastElement = arr.sort((a, b) => b[b.length - 1] - a[a.length - 1])[0]

CodePudding user response：

Another way to get max item with reduce

const arr = [[1,2,3], [3,4,5], [4,5,6], [7,8,9]];

const result = arr.reduce((max, item) => max.at(-1) > item.at(-1) ? max : item);

console.log(...result);

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