JSON

Parse

Bind to JavaScript's JSON.parse and type the return value as the type you're expecting:

// declare the shape of the json you're binding to
type data = {names: array<string>}

// bind to JS' JSON.parse
@scope("JSON") @val
external parseIntoMyData: string => data = "parse"

let result = parseIntoMyData(`{"names": ["Luke", "Christine"]}`)
let name1 = result.names[0]

Where data can be any type you assume the JSON is. As you can see, this compiles to a straightforward JSON.parse call. As with regular JS, this is convenient, but has no guarantee that e.g. the data is correctly shaped, or even syntactically valid. Slightly dangerous.

Stringify

Use Js.Json.stringify:

Console.log(Js.Json.stringifyAny(["Amy", "Joe"]))

Advanced

The Js.Json module provides slightly safer, low-level building blocks for power users who want to parse JSON on a per-field basis. See the examples in the API docs.