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

Iterate Object Properties in Reverse

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.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that iterates over an object's keys in reverse order and logs each key-value pair.
• Write a JavaScript function that retrieves an object's keys, reverses the order, and processes each property with a callback.
• Write a JavaScript program that uses Object.keys() and reverse() to iterate through properties backwards.
• Write a JavaScript function that returns an array of key-value pairs from an object in reverse key order.

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