codekingpro/portable-devtools

1const COMMA = ',';
2const COLON = ':';
3const LEFT_SQUARE_BRACKET = '[';
4const RIGHT_SQUARE_BRACKET = ']';
5const LEFT_CURLY_BRACKET = '{';
6const RIGHT_CURLY_BRACKET = '}';
7
8// Recursively encodes the supplied object according to the canonical JSON form
9// as specified at http://wiki.laptop.org/go/Canonical_JSON. It's a restricted
10// dialect of JSON in which keys are lexically sorted, floats are not allowed,
11// and only double quotes and backslashes are escaped.
12function canonicalize(object) {
13  const buffer = [];
14  if (typeof object === 'string') {
15    buffer.push(canonicalizeString(object));
16  } else if (typeof object === 'boolean') {
17    buffer.push(JSON.stringify(object));
18  } else if (Number.isInteger(object)) {
19    buffer.push(JSON.stringify(object));
20  } else if (object === null) {
21    buffer.push(JSON.stringify(object));
22  } else if (Array.isArray(object)) {
23    buffer.push(LEFT_SQUARE_BRACKET);
24    let first = true;
25    object.forEach((element) => {
26      if (!first) {
27        buffer.push(COMMA);
28      }
29      first = false;
30      buffer.push(canonicalize(element));
31    });
32    buffer.push(RIGHT_SQUARE_BRACKET);
33  } else if (typeof object === 'object') {
34    buffer.push(LEFT_CURLY_BRACKET);
35    let first = true;
36    Object.keys(object)
37      .sort()
38      .forEach((property) => {
39        if (!first) {
40          buffer.push(COMMA);
41        }
42        first = false;
43        buffer.push(canonicalizeString(property));
44        buffer.push(COLON);
45        buffer.push(canonicalize(object[property]));
46      });
47    buffer.push(RIGHT_CURLY_BRACKET);
48  } else {
49    throw new TypeError('cannot encode ' + object.toString());
50  }
51
52  return buffer.join('');
53}
54
55// String canonicalization consists of escaping backslash (\) and double
56// quote (") characters and wrapping the resulting string in double quotes.
57function canonicalizeString(string) {
58  const escapedString = string.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
59  return '"' + escapedString + '"';
60}
61
62module.exports = {
63  canonicalize,
64};
65