Parsing interview questions

Implement a function that checks whether a string of brackets is properly opened and closed in order.

Convert a Roman numeral string to its integer value, handling subtractive pairs like IV and IX.

Implement a function that wraps occurrences of a search term within a string in highlight markup.

Tokenize and evaluate a math expression string with operator precedence, parentheses, and unary minus.

Convert a number's string representation between any two bases from 2 to 36 — parse the digits in the source base, then re-emit them in the target base.

Convert any string between camelCase, snake_case, kebab-case, and PascalCase by tokenizing it into words first.

Implement a function that counts how many ways a digit string can be decoded into letters using a 1 to 26 mapping.

Implement a function that safely reads a nested object path and returns a default when any segment is missing.

Build a translation engine with nested key lookup, variable interpolation, pluralization, and locale fallback.

Parse and format ICU MessageFormat strings with plural, select, and nested argument substitution.

Validate IPv4 dotted-quad and IPv6 addresses, handling octet ranges, leading zeros, and :: zero-group compression.

Implement lodash-style set and unset: write or delete a value at a deep object path, creating containers as needed.

Parse and compare two semantic version strings — major, minor, patch, and prerelease — returning -1, 0, or 1 with correct prerelease precedence.

Implement a spreadsheet class that resolves numeric cell values and evaluates simple addition formulas.

Build a spreadsheet class that evaluates left-to-right arithmetic formulas referencing other cells.

Decode a Server-Sent Events stream arriving in arbitrary chunks into discrete parsed events.

Reimplement JavaScript's parseInt — skip leading whitespace, read an optional sign and radix prefix, consume valid digits for the base, and stop at the first invalid character.

Implement a template renderer that substitutes Mustache-style placeholders with values from a data object.

Implement a function that wraps every occurrence of any term from a list inside highlight markup.

Track streaming LLM tool calls by id, accumulating argument deltas and guarding each pending, running, and done transition.

Implement a function that rebuilds a nested object from a flat map of dot-delimited keys.

Implement a URLSearchParams-style class with get, getAll, append, set, and toString over an encoded query string.

Implement a function that filters an array of row objects by a flexible field-and-condition specification.

Implement JSON.parse — a recursive-descent parser that turns a JSON string into the corresponding JavaScript value.

Parse a truncated JSON string into the best-valid value so far by completing open strings and containers.

Build a grid of cells with formula evaluation and dependent-cell recalculation.

Render markdown-so-far to HTML, holding and closing unclosed bold, inline code, and fenced code blocks.

Implement serialize and deserialize helpers that round-trip values like Date, Map, Set, and BigInt through JSON.

Implement a function that walks an HTML document's headings and builds a nested table of contents.