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index.js
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index.js
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const COMMA = ',';
const COLON = ':';
const LEFT_SQUARE_BRACKET = '[';
const RIGHT_SQUARE_BRACKET = ']';
const LEFT_CURLY_BRACKET = '{';
const RIGHT_CURLY_BRACKET = '}';
// Recursively encodes the supplied object according to the canonical JSON form
// as specified at http://wiki.laptop.org/go/Canonical_JSON. It's a restricted
// dialect of JSON in which keys are lexically sorted, floats are not allowed,
// and only double quotes and backslashes are escaped.
function canonicalize(object) {
const buffer = [];
if (typeof object === 'string') {
buffer.push(canonicalizeString(object));
} else if (typeof object === 'boolean') {
buffer.push(JSON.stringify(object));
} else if (Number.isInteger(object)) {
buffer.push(JSON.stringify(object));
} else if (object === null) {
buffer.push(JSON.stringify(object));
} else if (Array.isArray(object)) {
buffer.push(LEFT_SQUARE_BRACKET);
let first = true;
object.forEach((element) => {
if (!first) {
buffer.push(COMMA);
}
first = false;
buffer.push(canonicalize(element));
});
buffer.push(RIGHT_SQUARE_BRACKET);
} else if (typeof object === 'object') {
buffer.push(LEFT_CURLY_BRACKET);
let first = true;
Object.keys(object)
.sort()
.forEach((property) => {
if (!first) {
buffer.push(COMMA);
}
first = false;
buffer.push(canonicalizeString(property));
buffer.push(COLON);
buffer.push(canonicalize(object[property]));
});
buffer.push(RIGHT_CURLY_BRACKET);
} else {
throw new TypeError('cannot encode ' + object.toString());
}
return buffer.join('');
}
// String canonicalization consists of escaping backslash (\) and double
// quote (") characters and wrapping the resulting string in double quotes.
function canonicalizeString(string) {
const escapedString = string.replace(/\\/g, '\\\\').replace(/"/g, '\\"');
return '"' + escapedString + '"';
}
module.exports = {
canonicalize,
};