Loop Through Nested Array Elements With JavaScript

Question

I'm trying to loop through nested arrays to determine if an element in the array is either "open" or "senior":

function openOrSenior(data) {
 for (let i = 0; i <= data.length; i++) {
 let dataElement = data[i];
 for (let j = 0; j <= dataElement.length; j++) {
 if (dataElement[0] >= 55 && dataElement[1] > 7) {
 return ["Senior"];
 }
 return ["Open"];
 }
 }
}

Given the input of

[[18, 20],[45, 2],[61, 12],[37, 6],[21, 21],[78, 9]]

The function should output

["Open", "Open", "Senior", "Open", "Open", "Senior"]

But currently it looks like it's only looping through the first element in the main array ([18, 20]) because my function is only returning:

["Open"]

Why is this function failing to continue to loop through the other nested arrays and return either "Open" or "Senior"? Possibly a problem with the scope?

https://www.codewars.com/kata/categorize-new-member/train/javascript

I was trying to implement what I found here, which suggested a for-loop within a for-loop.

• Edvaldo Silva de Almeida Jr: Why do you need the second loop? There are only two elements in dataElement and you are mentioning them by index, so why the second loop?
• HappyHands31: Oh yes, true - removing the second for-loop still returns, [Open], though.

Answer 1

You are returning whenever the check succeeds or not, and you've got a redundant for loop. You should iterate the array with a single for loop, and according to the check push Senior or Open to the result array. In the end return the result array.

function openOrSenior(data) {
 const result = [];
 for (let i = 0; i < data.length; i++) {
 const dataElement = data[i];
 if (dataElement[0] >= 55 && dataElement[1] > 7) {
 result.push("Senior");
 } else result.push("Open");
 }
 return result;
}
console.log(openOrSenior([[18, 20],[45, 2],[61, 12],[37, 6],[21, 21],[78, 9]]));

Or you can use Array.map():

const openOrSenior = data => 
 data.map(([a, b]) => 
 a >= 55 && b > 7 ? 'Senior' : 'Open'
 )
console.log(openOrSenior([[18, 20],[45, 2],[61, 12],[37, 6],[21, 21],[78, 9]]))

Answer 2

You need only a single loop and an array for the values.

function openOrSenior(data) {
 var result = [];
 for (let i = 0; i < data.length; i++) {
 let [left, right] = data[i];
 result.push(left >= 55 && right > 7
 ? "Senior"
 : "Open"
 );
 }
 return result;
}
console.log(openOrSenior([[18, 20], [45, 2], [61, 12], [37, 6], [21, 21], [78, 9]]));