## Problem Implement a simplified in-memory DOM tree. Each node has a `tag`, optional `id`, a list of `classes`, and child nodes. ```python class DOMNode: def __init__(self, tag: str, id: str = "", classes: list[str] = []): ... def append_child(self, child: 'DOMNode') -> None: ... def query_selector(self, selector: str) -> 'DOMNode | None': # supports: "tag", "#id", ".class", "tag.class" def query_selector_all(self, selector: str) -> list['DOMNode']: def remove_child(self, child: 'DOMNode') -> bool: ``` ## Example ```javascript // equivalent structure: // // ... // ... // root.query_selector(".intro") // -> first root.query_selector_all(".intro") // -> [ , ] root.query_selector("#root") // -> root div ``` ## Follow-ups 1. How would you support a descendant combinator, e.g., `"div p"` (all ` ` inside ` `)? 2. Implement `innerHTML` that serializes the subtree back to an HTML string. 3. What traversal strategy does `query_selector` use? Why BFS vs. DFS matters here. 4. How do you handle `query_selector` on a very deep tree (10K levels) without stack overflow?

InterviewDB Experience · Los Angeles

DOM Tree Manipulation - Build and Query a Simplified HTML DOM

phone

Interview Experience

Problem Implement a simplified in-memory DOM tree. Each node has a tag, optional id, a list of classes, and child nodes. Example Follow-ups How would you support a descendant combinator, e.g., "div p" (all <p> inside <div>)? Implement innerHTML that serializes the subtree back to an HTML string. What traversal strategy does query_selector use? Why BFS vs. DFS matters here. How do you handle query_selector on a very deep tree (10K levels) without stack overflow?

Full Details

🔒

Unlock all Affirm questions

Full insider details, leaked discussions, and candidate experiences.

Get full access — $100 a year, unlimited access

About This Question

This is a candidate experience report from a affirm interview during the phone round.

It covers the following topics: Strings, Phone, Graph, Coding, Onsite, Stack .

Topics

Strings Phone Graph Coding Onsite Stack

DOM Tree Manipulation - Build and Query a Simplified HTML DOM

Interview Experience

Full Details

About This Question

Topics

More Affirm Interview Questions