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JSON

Parse

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

Reason (Old Syntax)ML (Older Syntax)JS Output
 
// declare the shape of the json you're binding to
type data = {names: array(string)};

// bind to JS' JSON.parse
[@bs.scope "JSON"] [@bs.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:

Reason (Old Syntax)ML (Older Syntax)JS Output
 
Js.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.