JavaScript: Creates an object from an array, using the specified key and excluding it from each value

Last update on May 30 2022 10:00:47 (UTC/GMT +8 hours)

JavaScript Array: Exercise-44 with Solution

Write a JavaScript function to create an object from an array, using the specified key and excluding it from each value.

Use Array.prototype.reduce() to create an object from arr.
Use object destructuring to get the value of the given key and the associated data and add the key-value pair to the object.

Sample Solution:

JavaScript Code :

//Source:https://bit.ly/3hEZdCl
//Add the key-value pair to the object.
const indexOn = (arr, key) =>
  arr.reduce((obj, v) => {
    const { [key]: id, ...data } = v;
    obj[id] = data;
    return obj;
  }, {});
 
console.log(indexOn([
  { id: 10, name: 'apple' },
  { id: 20, name: 'orange' }
], x => x.id));

Sample Output:

{"undefined":{"id":20,"name":"orange"}}

Flowchart :

Live Demo :

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

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