Loading challenge...
Preparing the challenge details...
Starter#Objects#Drills
JS Object Transformations Drill
Practice the object transformation patterns interviewers love — group by, flatten, invert, pick, omit, deep merge, and more. 15 quick drills with instant feedback.
By modernDev2026-03-20
A focused drill set covering the most common object transformation patterns in JavaScript interviews. Write a solve(input) function for each problem and get instant pass/fail feedback. Covers Object.fromEntries, Object.entries, reduce, recursion, and more.
Goal: Complete all 15 object transformation drills. Aim to solve each without hints!
Related Challenges
Continue learning with these related challenges
Recursive Object Evaluation
JavaScriptImplement a function that recursively traverses an object, evaluates functions with given arguments, and transforms keys to lowercase. Master recursive object traversal and type checking.
JavaScriptRecursionObjects
JS Output Challenges
JavaScriptTest your JavaScript skills by predicting console output for tricky code snippets. Covers hoisting, closures, this binding, async operations, and event loop quiz questions.
JavaScriptES6
Get smart in javascript
JavaScriptLevel up your JavaScript expertise with advanced tips, tricks, and gotchas. Master closures, hoisting, coercion, and event loop behavior to write cleaner, bug-free code.
JavaScriptES6
JavaScript
Recursive Object Evaluation
Implement a function that recursively traverses an object, evaluates functions with given arguments, and transforms keys to lowercase. Master recursive object traversal and type checking.
JavaScriptRecursionObjects
JavaScript
JS Output Challenges
Test your JavaScript skills by predicting console output for tricky code snippets. Covers hoisting, closures, this binding, async operations, and event loop quiz questions.
JavaScriptES6
JavaScript
Get smart in javascript
Level up your JavaScript expertise with advanced tips, tricks, and gotchas. Master closures, hoisting, coercion, and event loop behavior to write cleaner, bug-free code.
JavaScriptES6