JavaScript: Iterate over all own properties of an object in reverse, running a callback for each one

JavaScript fundamental (ES6 Syntax): Exercise-231 with Solution

Write a JavaScript program to iterate over all the properties of an object in reverse, running a callback for each one.

• Use Object.keys(obj) to get all the properties of the object, Array.prototype.reverse() to reverse their order.
• Use Array.prototype.forEach() to run the provided function for each key-value pair.
• The callback receives three arguments - the value, the key and the object.

Sample Solution:

JavaScript Code:

// Define a function 'forOwnRight' that iterates over an object's own properties in reverse order and executes a function for each property
const forOwnRight = (obj, fn) =>
  // Get the keys of the object, reverse their order, and iterate over them
  Object.keys(obj)
    .reverse()
    .forEach(key => fn(obj[key], key, obj));

// Test the 'forOwnRight' function by logging the values of each property in reverse order
console.log(forOwnRight({ foo: 'bar', a: 1 }, v => console.log(v)));

Output:

1
bar
undefined

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-231-1 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to get the human readable format of the given number of milliseconds.
Next: Write a JavaScript program that takes a function as an argument, then makes the first argument the last.