Hi. I need some help with this kata (CodeWars challenge) in JavaScript. Basically, it wants you to reorder a given array, pop and shift off the highest and lowest, then add the remaining elements together. The challenge can be found here: https://www.codewars.com/kata/576b93db1129fcf2200001e6/train/javascript.
I just need some help figuring out what’s going wrong. Here’s the code I have so far:
function sumArray(array) { //get input
var numArray = array.sort((a, b) => a - b); //rearrange array order from min to max
var poppednumArray = numArray.pop(); //pop and shift
var shiftedArray = poppedArray.shift(); //return array -pop and -shift
var i;
var s = 0;
for (i = 0; i < shiftedArray.length; i++){
s = s + [i];//add elements together = sum
}//ends for loop
return shiftedArray; //return sum
}
Currently, it’s telling me that I don’t have some variables declared.
ReferenceError: poppedArray is not defined
at sumArray
at /home/codewarrior/index.js:19:23
at /home/codewarrior/index.js:20:5
at Object.handleError
<anonymous>
It seems like I do, and I’ve switched around let/var, defined them on separate lines, to no luck, so I’m a little confused.
Any help would be appreciated. Thanks!
I don’t see a poppedArray too, I see
var poppednumArray = numArray.pop();
poppednumArray
Hope this helps 
1 Like
Thanks for the catch, but I fixed it and now it’s throwing a similar error:
TypeError: poppedArray.shift is not a function
at sumArray
at /home/codewarrior/index.js:19:23
at /home/codewarrior/index.js:20:5
at Object.handleError
<anonymous>
.shift() is just a method, right? Why does it seem to treat poppedArray() as a new function?
.sort()
.slice()
.reduce()
use those.
1 Like
You didn’t post your “fix” so can’t really say what the issue is.
But the error implies your “poppedArray” variable is not an array.
1 Like
I just fixed the name of that variable and didn’t have much time to mess with it much more until now:
function sumArray(array) { //get input
var numArray = array.sort((a, b) => a - b); //rearrange array order from min to max
var poppedArray = numArray.pop(); //pop and shift
var shiftedArray = poppedArray.shift(); //return array -pop and -shift
var i;
var s = 0;
for (i = 0; i < shiftedArray.length; i++){
s = s + [i];//add elements together = sum
}//ends for loop
return shiftedArray; //return sum
}
is what it ended up looking like.
var poppedArray = numArray.pop();
makes poppedArray a single value.
example:
let myNumbers = [1,2,3,4,5];
let example = myNumbers.pop();
console.log(example); // 1
console.log(myNumbers); // [2,3,4,5];
var shiftedArray = poppedArray.shift(); // error because .shift() is a method for arrays.
1 Like
I guess I should have mentioned that the inputs from the problem are arrays:
Sum all the numbers of the array (in F# and Haskell you get a list) except the highest and the lowest element (the value, not the index!).
(The highest/lowest element is respectively only one element at each edge, even if there are more than one with the same value!)
Example:
{ 6, 2, 1, 8, 10 } => 16
{ 1, 1, 11, 2, 3 } => 6
Those are not Javascript arrays.
But if you follow my advice earlier., you’ll want to use sort,. to get min and max on ends., slice() to get the numbers in middle and reduce to reduce your array into a single value.
1 Like
.shift(), .pop() work too,. I just never use them because they mutate the original value. I stay away from methods that do that.
1 Like
Ok. I’m not sure why it’s phrased like that, then. I followed your suggestion and got:
function sumArray(find_average) {
var numArray = find_average.sort(function(a, b){return a-b});//sorts array in ascending order
var sliceArray = numArray.slice([0],[-1]);//slices off ends of array
var sum = sliceArray.reduce((total, amount) => total + amount);//add remaining array together
return sum;
}
and now it’s throwing
ReferenceError: find_average is not defined
at /home/codewarrior/index.js:14:10
at /home/codewarrior/index.js:16:5
at Object.handleError
<anonymous>
Ok, I kind of shifted it around a little and got:
function find_average(array) {
var numArray = find_average.sort(function(a, b){return a-b});//sorts array in ascending order
var sliceArray = numArray.slice([0],[-1]);//slices off ends of array
var sum = sliceArray.reduce((total, amount) => total + amount);//add remaining array together
return sum;
}
but it throws:
TypeError: find_average.sort is not a function
at find_average
at /home/codewarrior/index.js:14:23
at /home/codewarrior/index.js:16:5
at Object.handleError
<anonymous>
Not sure why you called it “find_average”… You’re not looking for an average.
Don’t ever use var.
slice([0], [-1]) is not correct syntax. You may want to consider researching these methods you’re using.
Mainly .slice(); // im confident if you check it out,. you’ll see how to use it.
function sumArray(arr){
const sortedArr = arr.sort(function(a, b){
return a - b;
});
}
The error you’re pasting suggests your variable is in a TDZ. Check and ensure you have selected Javascript as the language to solve this problem.
1 Like
Sorry, I had two open and got confused. Yeah, they’re both in JS.
Oddly enough,. the .slice([a], [b]) works,. but it’s not usually written that way.
1 Like
Ok, so
function sumArray(array) {
function sumArray.sort(function(a, b){return a-b});//sorts array in ascending order
let sliceArray = sumArray.slice([1],[-1]);//slices off ends of array
let sum = sliceArray.reduce((total, amount) => total + amount);//add remaining array together
return sum;
}
is what I got. It throws:
/home/codewarrior/index.js:6
function sumArray.sort(function(a, b){return a-b});//sorts array in ascending order
^
SyntaxError: Unexpected token .
at createScript (vm.js:80:10)
at Object.runInThisContext (vm.js:139:10)
at Module._compile (module.js:616:28)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Module.require (module.js:596:17)
at require (internal/module.js:11:18)
at [eval]:1:1
Subtracting min and max after iterating it once.
1 Like
I don’t understand. I have “function sumArray.sort(…”