281. Lodash `get`

Implement a get(object, path, defaultValue) function similar to Lodash's _.get().

It safely accesses deeply nested properties without throwing errors when intermediate values are null or undefined.

Requirements

1. Core Behavior

• path can be a string like 'a.b.c' or 'a[0].b'
• path can also be an array like ['a', 'b', 'c']
• Return the value at the path, or defaultValue if the resolved value is undefined

2. Path Parsing

• Dot notation: 'a.b.c' → keys ['a', 'b', 'c']
• Bracket notation: 'a[0].b' → keys ['a', '0', 'b']
• Mixed: 'a.b[0].c' → keys ['a', 'b', '0', 'c']
• Array path: ['a', '0', 'b'] → keys used directly

3. Edge Cases

• null or undefined as the object → return defaultValue
• null in the path → return defaultValue (can't traverse further)
• Value is null → return null (not the default)
• Value is undefined → return defaultValue
• Value is 0, false, '' → return the value (not the default)

Example Usage

const obj = { a: { b: [{ c: 42 }] } };

get(obj, 'a.b[0].c');        // 42
get(obj, 'a.b[0].d', 'N/A'); // 'N/A'
get(obj, ['a', 'b', '0']);   // { c: 42 }
get(null, 'a.b', 'default'); // 'default'

Real-World Context

• API response handling: Safely accessing nested API data without ?. chains
• Configuration objects: Accessing deeply nested config with fallback defaults
• Form state: Accessing nested form values like 'address.city' in React Hook Form