JavaScript: Ungrouping the elements in an array produced by zip

Last update on May 30 2022 10:01:31 (UTC/GMT +8 hours)

JavaScript Array: Exercise-43 with Solution

Write a JavaScript function to create an array of arrays, ungrouping the elements in an array produced by zip.

Use Math.max(), Function.prototype.apply() to get the longest subarray in the array, Array.prototype.map() to make each element an array.
Use Array.prototype.reduce() and Array.prototype.forEach() to map grouped values to individual arrays.

Sample Solution:

JavaScript Code :

//Source:https://bit.ly/3hEZdCl
//unzip
const unzip = arr =>
  arr.reduce(
    (acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc),
    Array.from({
      length: Math.max(...arr.map(x => x.length))
    }).map(x => [])
  );
console.log(unzip([['a', 1, true], ['b', 2, false]]));
console.log(unzip([['a', 1, true], ['b', 2]]));

Sample Output:

[["a","b"],[1,2],[true,false]]
[["a","b"],[1,2],[true]]

Flowchart :

Live Demo :

See the Pen javascript-common-editor by w3resource (@w3resource) on CodePen.

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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04