Missing comma in JSON

Items in a JSON object or list are separated by commas. When one is missing, the parser reads the next key or value where it expected a comma or a closing bracket, so the error points at the start of the next item, often on the line after the real problem. It usually happens when a line is added at the end of an object and the line above doesn't get a comma.

In Chrome and Node.js, JSON.parse says: Expected ',' or '}' after property value in JSON

Broken
{
  "name": "Ada Lovelace",
  "born": 1815
  "field": "mathematics"
}
Fixed
{
  "name": "Ada Lovelace",
  "born": 1815,
  "field": "mathematics"
}

Fix it by hand

Add a comma at the end of the item before the one the error points to.

Open this example in j2n