Sort an array except one element in JavaScript

Question

I have an array and I am sorting it but I need to sort everything except one element of my array.

My array is:

var Comparison = [
    {key: \"None\", val         


        

Answer 1

Alternatively you can filter out the nones and sort the other elements. Then concatenate them back to each other at the end.

const comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

const result = comparison
               .filter(e => e.key === 'None')
               .concat(
                 comparison.filter(e => e.key !== 'None')
                           .sort((a, b) => a.key.localeCompare(b.key))
               );
               
console.log(result);

Explanation:

const comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

// fetch all elements with the key 'None'
const nones = comparison.filter(e => e.key === 'None');
// fetch all elements with the key not 'None'
const others = comparison.filter(e => e.key !== 'None')
// sort the elements in the array by key
                         .sort((a, b) => a.key.localeCompare(b.key));
// concatenate the 2 arrays together
const result = nones.concat(others);

console.log(result);

A bit of credit to Pac0s answer. After writing my solution I saw that I basically made a working version of his explanation. I'm too late to add my example to his answer because this is currently the most upvoted of the two.

---

For larger arrays using filter() two times on the same array with the opposite predicate (check callback) might be a bit inefficient. You could opt to introduce a helper function like partition() to help reduce the amount of iteration that has to be done.

function partition(forEachable, callback) {
  const partitions = { "true": [], "false": [] };
  forEachable.forEach((...args) => partitions[!!callback(...args)].push(args[0]));
  return [partitions[true], partitions[false]];
}

let comparison = [{key: "None", value: "None"}, {key: "Geographical Area", value: "Geographical_Area"}, {key: "Forests", value: "Forests"}, {key: "Barren Unculturable Land", value: "Barren_Unculturable_Land"}, {key: "Land put to Non agricultural use", value: "Land_put_to_Non_agricultural_use"}, {key: "Land Area", value: "Land_Area"}, {key: "Water Area", value: "Water_Area"}, {key: "Culturable Waste", value: "Culturable_Waste"}, {key: "Permanent Pastures", value: "Permanent_Pastures"}, {key: "Land under Tree Crops", value: "Land_under_Tree_Crops"}, {key: "Fallow Land excl Current Fallow", value: "Fallow_Land_excl_Current_Fallow"}, {key: "Current Fallow", value: "Current_Fallow"}, {key: "Total Unculturable Land", value: "Total_Unculturable_Land"}, {key: "Net Sown Area", value: "Net_Sown_Area"}, {key: "Gross Sown Area", value: "Gross_Sown_Area"}, {key: "Cropping Intensity", value: "Cropping_Intensity"}];

const [nones, others] = partition(comparison, e => e.key === "None");
others.sort((a, b) => a.key.localeCompare(b.key));
const result = nones.concat(others);
console.log(result);