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I am looking for a way to reorder the beneath array of nested arrays in a specific order. The values within the exposureLevel array come in any order when imported.

var exposureLevel = [["Exposure Level","Number"],["High",15],["Low",38],["Medium",105],["None",156]];

Some of these values can also be missing from the exposureLevel array. Beneath are some possible examples of this:

[["Exposure Level","Number"],["Low",38],["Medium",105]];
[["Exposure Level","Number"],["High",15],["None",156]];
[["Exposure Level","Number"],["High",15],["Medium",105],["None",156]];

I would like the array to be in the order beneath, starting with the [1] element after the heading being None, Low, Medium, High. The three arrays beneath show how I'd like the three examples above to output. I'm not entirely sure how to do this, but I'd have to have some type of check where the string values within the sub-arrays are compared and that entire sub-array's position in the parent array is adjusted.

[["Exposure Level","Number"],["Low",38],["Medium",105]];
[["Exposure Level","Number"],["None",156],["High",15]];
[["Exposure Level","Number"],["None",156],["Medium",105],["High",15]];

I have looked at these posts prior to posting this but haven't had a great deal of success:

  1. For-each over an array in JavaScript
  2. JOLT - Reorder nested arrays
  3. How do I check if an array includes a value in JavaScript?
  4. Javascript array contains/includes sub array

My current solution:

for (let i = 0; i < exposureLevel.length; i++) {

  if(exposureLevel[i][0] == "None"){
    console.log(exposureLevel[i][0])
  } 
  if(exposureLevel[i][0] == "Low"){
    console.log(exposureLevel[i][0])
  } 
  if(exposureLevel[i][0] == "Medium"){
    console.log(exposureLevel[i][0])
  } 
  if(exposureLevel[i][0] == "High"){
    //not sure how to push onto array correctly
    console.log(exposureLevel[i][0])
  }

}

I understand my current solution doesn't do anything, but I've managed to isolate the string in each sub-array. The next step is to push the entire array into a new array in the specified order. If anyone knows a better way to do the above, please let me know.

I have little experience with JS. If someone could assist me with this or point me in the right direction I'd greatly appreciate it. Please let me know if there's any further information that is needed. Thanks.

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3 Answers 3

Reset to default
1

Array.sort with mapping of keys to another setting orders

const exposureLevel = [["Exposure Level","Number"],["High",15],["Low",38],["Medium",105],["None",156]];
const orders = { None: 1, Low: 2, Medium: 3, High: 4 };
const sorted = exposureLevel.sort((a, b) => (orders[a[0]] || 0) - (orders[b[0]] || 0));
console.log(sorted);

Reference: Array.sort()

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4 Comments

Thanks for helping me. I was not aware that you could set the order like that. What happens if the values change? As sometimes they come in different.
@geojoe what values do you refer to?
The numeric values within the sub-arrays
@geojoe they do not affect sorting orders, any numbers will do.
1

Use an object to define your sort order, and use that in your comparator:

const o = {None: 0, Low: 1, Medium: 2, High: 3};

const sort = ([h, ...v]) => [h, ...v.sort(([l1], [l2]) => o[l1] - o[l2])];

console.log(sort([["Exposure Level","Number"],["Low",38],["Medium",105]]));
console.log(sort([["Exposure Level","Number"],["High",15],["None",156]]));
console.log(sort([["Exposure Level","Number"],["High",15],["Medium",105],["None",156]]));

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1 Comment

Thanks Robby, this solution also works great.
1

Use Array.sort to sort the array.

Logic

  • Make use of a reference array order to keep track of the order of output.
  • Sort the array based on the index of the labels from the reference order array.

const order = ["Exposure Level", "None", "Low", "Medium", "High"];
var exposureLevel = [
  ["Exposure Level","Number"],
  ["High",15],
  ["Low",38],
  ["Medium",105],
  ["None",156],
];
exposureLevel.sort((a, b) => {
  // Should return -1, 0 or +1
  if (order.indexOf(a[0]) > order.indexOf(b[0])) return 1;
  else if (order.indexOf(a[0]) < order.indexOf(b[0])) return -1;
  else return 0;
});
console.log(exposureLevel);

One Liner Solution

const order = ["Exposure Level", "None", "Low", "Medium", "High"];
const exposureLevel = [["Exposure Level","Number"], ["High",15], ["Low",38], ["Medium",105], ["None",156]];
exposureLevel.sort((a, b) => order.indexOf(a[0]) - order.indexOf(b[0]));
console.log(exposureLevel);

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2 Comments

Thanks Nitheesh. This also works well. However, is slightly longer than other solutions.
@geojoe Longer by line of codes? My solution can also be inplemented in oneline. I put the detailed solution for our understanding. Pease see the updated answer with 4 line of code.

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