# Return Largest Numbers in Arrays (syntax error?)

Return Largest Numbers in Arrays (syntax error?)
0

#1

In this code challenge we need to return the biggest number in sub arrays, then combine them into an array.

for example:

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

So, here’s what I am planning to do:

1. create a inner function, to return all the biggest number inside the sub-array. for example: [13,27,18,26] will give you 27.
2. Create an outer function, to combine all those 4 numbers into one array and output it.

And here’s what the inner function looks like:

``````function extract(arr){
var base = 0;

for(let i = 0; i< arr.length; i++){
while(arr[i]>base){
base = arr[i];
}
}

return base;
}

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

It works.

and here’s the outer function (unfinished) :

``````function a(arr){
for(var j=0;j<arr.length;j++){
function extract(arr[j]){ //this is where the error comes from
var base = 0;
for(let i = 0;i<arr[j].length;i++){
while(arr[j][i]>base){
base = arr[j][i];
}
}
console.log(base);
}
}
}

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

And it gives me an error there, at the 3rd line.
How do I change its syntax so that it wont give me an error?

#2

were you trying to “return” the function?
Right now you are just defining it without assigning to anything (no variable, no return)

#3

I know that it returns undefined.
I will change that part later.

But the error I get says at 3rd line I cannot use arr[j] .
Then how am I gonna use code to represent the inner arrays?

#4

arr[j] is not a valid parameter name

I’m not clear if you are trying to return a function definition or define and use an anonymous function.

If you want to pass arr[j] to your anonymous function, then assign it to some variable (after you change the param to valid variable name) and then pass arr[j] to that new variable function.

Not sure if I’m helping, but I hope I’m giving you an idea…

edit , here’s an example using your function:

let myfunc = function extract(arr){
var base = 0;

for(let i = 0; i< arr.length; i++){
while(arr[i]>base){
base = arr[i];
}
}

return base;
};

myfunc(arr[j]);

#5

I see… so one of the problem I have here is that I declared a function but did not invoke it.
I will try to figure out the rest myself…

Thanks!