JSON

Table of contents

1. 1. JSON structure and syntax

   6 tasks · 6 interviews· 48 min
   • Identify the six structural characters of JSON
   • Distinguish a valid JSON document from an invalid one by eye
   • Write a minimal valid JSON document from scratch

   json-syntax

2. 2. The six value types

   10 tasks · 9 interviews· 1 h 27 m
   • Name all six JSON value types and give a literal example of each
   • Explain why null, true, and false must be unquoted and lowercase
   • Distinguish string '42' from number 42 and null from false

   json-null-booljson-types

3. 3. Objects in depth

   6 tasks · 4 interviews· 54 min
   • Write a JSON object with multiple key-value pairs
   • Explain the rules for keys (must be double-quoted strings, must be unique)
   • Identify and fix a trailing-comma error in an object

   json-objects

4. 4. Arrays in depth

   4 tasks · 4 interviews· 29 min
   • Write a JSON array of strings, numbers, and mixed types
   • Explain that arrays are ordered and allow duplicates
   • Access elements by index when reading programmatically

   json-arrays

5. 5. Nested structures

   12 tasks · 7 interviews· 2 h 1 m
   • Write a JSON document with at least two levels of nesting
   • Pretty-print and minify a JSON document with Python
   • Read a deeply nested value with Python or jq

   json-formattingjson-nesting

6. 6. Reading and fixing parse errors — real-world configs

   5 tasks · 3 interviews· 47 min
   • Identify the line and character of a JSON parse error from the error message
   • Fix trailing commas, mismatched brackets, and single-quoted keys
   • Write a valid package.json and a GitHub Actions step in JSON

   json-parsing-errors