# Return Largest Number in Arrays

Tell us what’s happening:

Can return ‘ar’ and ‘len’ right but returns nothing for ‘arg’. The syntax seems right and it’s no runtime error. I don’t understand why ‘len’ isn’t ‘pushed’ to ‘arg’.

``````
function largestOfFour(ar) {
var arg = []; //to put the numbers in
var len = ar.length; //how many miniarrays there are
for(var x = 0; i<len; i++){ //loops the number of miniarrays
var lar = 0; //to store the biggest int of four
lar = ar; //lar = firstnum of miniarray
for(var i = 0; i<4; i++){ //four times (i = 0,1,2,3)
if(ar[i]>lar){lar=ar[i];} //sets lar equal if(i[1/2/3] are bigger than ar)
}
arg.push(lar);//pushes biggest num on arg
}
return arg; //returns arg
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);
``````

User Agent is: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36`.

1 Like

First problem is your for loop condition of i < len above. The variable i you are comparing to len is undefined when the for loop starts, so you are comparing undefined < len which evaluates to false, so the outer for loop never executes and all you do is return arg which is an empty array.

Next problem if you figure out what to put for the initial value and the condition expression of the outer for loop, is the line above. Think about what kind of value ar[i] is. Since ar is an array containing elements which are arrays, then ar[i] is an array, so your comparison to lar will always evaluate to false, so the lar=ar[i] will never execute.

Try using the Math.max and Math.min functions., here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/max

It worked, thanks ``````function largestOfFour(ar) {
var arg = []; //to put the numbers in
var len = ar.length; //how many miniarrays there are
for(var i = 0; i<len; i++){ //loops the number of miniarrays
var lar = 0; //to store the biggest int of four
lar = ar; //lar = firstnum of miniarray
lar = Math.max(...ar[i]); //to find the highest value of the four
arg.push(lar);//pushes biggest num on arg
}
return arg; //returns arg
}
``````

Or you can just return Math.max (…arr);

``````function largestOfFour (arr){
return Math.max (...arr);
}
``````