ErrorJSON · .json
JSON with Comments — Why Comments Break JSON Parsers
A JSON file containing JavaScript-style comments (// or /* */). Comments are not part of the JSON specification despite being common in config files.
Why It Fails
Douglas Crockford intentionally excluded comments from JSON to prevent misuse as a processing directive. JSON parsers treat comment characters as invalid syntax. JSONC and JSON5 are alternative formats that support comments.
Broken Example
{
// This is a comment
"name": "Alice",
/* Multi-line
comment */
"age": 30
}Expected Error Behavior
JSON.parse() throws SyntaxError. Config tools like VS Code use JSONC internally but standard JSON APIs reject comments.
Affected Software
JSON.parse()All standard JSON parsersREST APIsDatabase JSON columns
How to Fix
Remove all comments before parsing. Use JSONC or JSON5 format if comments are needed. Strip comments with a preprocessor.