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

JavaScript fundamental (ES6 Syntax): Exercise-77 with Solution

Iterate Over Object Properties

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

• Use Object.keys(obj) to get all the properties of the object.
• 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:

//#Source https://bit.ly/2neWfJ2
// Define the function 'forOwn' to iterate over an object's own enumerable properties and apply a callback function to each property.
const forOwn = (obj, fn) =>
  // Iterate over the keys of the object using Object.keys() and apply the callback function to each property.
  Object.keys(obj).forEach(key => fn(obj[key], key, obj));

// Example usage:
forOwn({ foo: 'bar', a: 1 }, v => console.log(v)); // Outputs: 'bar', 1

Output:

bar
1

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-76-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that iterates over all enumerable properties of an object and executes a callback for each.
• Write a JavaScript function that uses for...in to traverse an object and logs each key-value pair.
• Write a JavaScript program that collects an array of property names from an object while iterating over its properties.

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