API Relaxed JSON

Relaxed JSON is a JSON superset that that aims to be easier to write by humans.

Example

Unpoly often accepts JSON in HTML attributes or HTTP headers:

<span class='user' up-data='{ "name": "Bob", "age": 18 }'>Bob</span>

To be easier on the hand and eyes, Unpoly also accepts single-quoted strings and unquoted property names:

<span class="user" up-data="{ name: 'Bob', age: 18 }">Bob</span>

Syntax rules

• Every JSON object is also a Relaxed JSON object.
• Relaxed JSON allows single-quoted strings, in addition to double-quoted strings.
• Relaxed JSON allows unquoted property names, like JavaScript. It's also OK to double-quote property names.
• Relaxed JSON allows trailing commas in object literals and array literals.

Postel's law

When Unpoly outputs HTML (e.g. for the X-Up-Context header) it always produces regular JSON.

If you implement the optional server protocol you only need to deal with regular JSON strings.

Parsing relaxed JSON

Your frontend code can parse relaxed JSON using up.util.parseRelaxedJSON():

let value = up.util.parseRelaxedJSON("{ foo: 'one', bar: 'two', }")
console.log(value) // logs an object { foo: 'one', bar: 'two' }

On the backend we recommend using a JSON5 parser, which is a superset of relaxed JSON. JSON5 parsers are available in many languages.