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JSON.isRawJSON()

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The JSON.isRawJSON() static method tests whether a value is an object returned by JSON.rawJSON().

Syntax

JSON.isRawJSON(value)

Parameters

value: The value to test.

Return value

true if value is created by JSON.rawJSON(); otherwise, false.

Description

"Raw JSON" objects, when serialized to JSON, are treated as if they are already a piece of JSON. Furthermore, because of the way JSON.rawJSON() works, the raw JSON is guaranteed to be syntactically valid JSON. For more information on the shape and behavior of raw JSON objects, see JSON.rawJSON(). This method exists to allow other serialization libraries to implement similar behavior to JSON.stringify() for raw JSON objects.

Examples

Using JSON.isRawJSON()

The following example demonstrates how to use JSON.isRawJSON() to test whether an object was returned by JSON.rawJSON(). It implements a custom serializer that serializes data to a YAML-like format.

function mySerializer(value, indent = "") {
  if (typeof value !== "object" || value === null) {
    return JSON.stringify(value);
  }
  if (JSON.isRawJSON(value)) {
    return value.rawJSON;
  }
  const subIndent = `${indent}  `;
  if (Array.isArray(value)) {
    return `- ${value.map((v) => mySerializer(v, subIndent)).join(`\n${indent}- `)}`;
  }
  return Object.entries(value)
    .map(([key, value]) => {
      const subValue = mySerializer(value, subIndent);
      if (subValue.includes("\n")) {
        return `${key}:\n${subIndent}${subValue}`;
      }
      return `${key}: ${subValue}`;
    })
    .join(`\n${indent}`);
}

console.log(
  mySerializer({
    name: "Josh",
    userId: JSON.rawJSON("12345678901234567890"),
    friends: [
      { name: "Alice", userId: JSON.rawJSON("9876543210987654321") },
      { name: "Bob", userId: JSON.rawJSON("56789012345678901234") },
    ],
  }),
);

// name: "Josh"
// userId: 12345678901234567890
// friends:
//   - name: "Alice"
//     userId: 9876543210987654321
//   - name: "Bob"
//     userId: 56789012345678901234

If in the above example, the userId values were not created by JSON.rawJSON(), but passed as numbers directly, then we will get loss of precision upfront because of JS floating point precision limitations.

console.log(
  mySerializer({
    name: "Josh",
    userId: 12345678901234567890,
    friends: [
      { name: "Alice", userId: 9876543210987654321 },
      { name: "Bob", userId: 56789012345678901234 },
    ],
  }),
);

// name: "Josh"
// userId: 12345678901234567000
// friends:
//   - name: "Alice"
//     userId: 9876543210987655000
//   - name: "Bob"
//     userId: 56789012345678900000

Specifications

Specification
JSON.parse source text access> # sec-json.israwjson>

Browser compatibility

	Desktop					Mobile							Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	WebView on iOS	Bun	Deno	Node.js
`isRawJSON`	114	114	135	100	No	114	135	76	No	23.0	114	No	1.1.43	1.33	21.0.0