index.js 2.0 KB

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  1. const COMMA = ',';
  2. const COLON = ':';
  3. const LEFT_SQUARE_BRACKET = '[';
  4. const RIGHT_SQUARE_BRACKET = ']';
  5. const LEFT_CURLY_BRACKET = '{';
  6. const RIGHT_CURLY_BRACKET = '}';
  7. // Recursively encodes the supplied object according to the canonical JSON form
  8. // as specified at http://wiki.laptop.org/go/Canonical_JSON. It's a restricted
  9. // dialect of JSON in which keys are lexically sorted, floats are not allowed,
  10. // and only double quotes and backslashes are escaped.
  11. function canonicalize(object) {
  12. const buffer = [];
  13. if (typeof object === 'string') {
  14. buffer.push(canonicalizeString(object));
  15. } else if (typeof object === 'boolean') {
  16. buffer.push(JSON.stringify(object));
  17. } else if (Number.isInteger(object)) {
  18. buffer.push(JSON.stringify(object));
  19. } else if (object === null) {
  20. buffer.push(JSON.stringify(object));
  21. } else if (Array.isArray(object)) {
  22. buffer.push(LEFT_SQUARE_BRACKET);
  23. let first = true;
  24. object.forEach((element) => {
  25. if (!first) {
  26. buffer.push(COMMA);
  27. }
  28. first = false;
  29. buffer.push(canonicalize(element));
  30. });
  31. buffer.push(RIGHT_SQUARE_BRACKET);
  32. } else if (typeof object === 'object') {
  33. buffer.push(LEFT_CURLY_BRACKET);
  34. let first = true;
  35. Object.keys(object)
  36. .sort()
  37. .forEach((property) => {
  38. if (!first) {
  39. buffer.push(COMMA);
  40. }
  41. first = false;
  42. buffer.push(canonicalizeString(property));
  43. buffer.push(COLON);
  44. buffer.push(canonicalize(object[property]));
  45. });
  46. buffer.push(RIGHT_CURLY_BRACKET);
  47. } else {
  48. throw new TypeError('cannot encode ' + object.toString());
  49. }
  50. return buffer.join('');
  51. }
  52. // String canonicalization consists of escaping backslash (\) and double
  53. // quote (") characters and wrapping the resulting string in double quotes.
  54. function canonicalizeString(string) {
  55. const escapedString = string.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
  56. return '"' + escapedString + '"';
  57. }
  58. module.exports = {
  59. canonicalize,
  60. };