Skip to content

Latest commit

 

History

History
118 lines (93 loc) · 3.19 KB

index.md

File metadata and controls

118 lines (93 loc) · 3.19 KB
Raw
title slug page-type status browser-compat
JSON.isRawJSON()
Web/JavaScript/Reference/Global_Objects/JSON/isRawJSON
javascript-static-method
experimental
javascript.builtins.JSON.isRawJSON

{{JSRef}}{{SeeCompatTable}}

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

Syntax

JSON.isRawJSON(value)

Parameters

  • value
    • : The value to test.

Return value

true if value is created by {{jsxref("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 {{jsxref("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 {{jsxref("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

{{Specifications}}

Browser compatibility

{{Compat}}

See also