Common Mistakes in the Machine Coding Round

Common Mistakes in the Machine Coding Round

Many candidates fail the machine coding round due to avoidable mistakes. Here are the common ones and how to avoid each.

Mistake 1: Not Reading the Problem Carefully

Candidates skim the problem and miss requirements. They build the wrong thing.

Fix: read the problem twice. List the required features. Ask clarifying questions.

Mistake 2: Starting to Code Without a Plan

Candidates jump into code immediately. They rework constantly.

Fix: spend 5-10 minutes planning (HTML, state, events). A plan saves time.

Mistake 3: Building Everything at Once

Candidates try to build all features simultaneously. Nothing works until the end.

Fix: build the core first. Get it working. Then add features one by one.

Mistake 4: Ignoring Edge Cases

Candidates build the happy path and forget empty states, no results, and errors.

Fix: list edge cases during planning. Handle them after the core works.

Mistake 5: Messy Code

Candidates write one giant function with unclear variable names.

Fix: use small functions. Name variables clearly. Separate concerns.

Mistake 6: No CSS

Candidates submit raw HTML with no styling. It looks unfinished.

Fix: add basic CSS (padding, borders, hover states, centered container) in the last 10 minutes.

Mistake 7: Not Testing

Candidates submit without testing. Bugs go unfixed.

Fix: test with the examples from the problem. Test edge cases. Fix bugs.

Mistake 8: Spending Too Long on One Feature

Candidates perfect one feature and run out of time for the rest.

Fix: build core first. Move on. Come back to polish if time remains.

Mistake 9: Not Communicating

Candidates code silently. The interviewer cannot evaluate their thinking.

Fix: explain what you are building. Ask questions. Discuss trade-offs.

Mistake 10: Panicking

Candidates panic when something does not work. They freeze or make rash changes.

Fix: stay calm. Debug step by step. Use console.log to inspect. Ask for a hint if truly stuck.

The Takeaway

Avoid these mistakes: not reading carefully, no plan, building everything at once, ignoring edge cases, messy code, no CSS, not testing, spending too long on one feature, not communicating, and panicking. Preparation and calm execution are key.