Function stringifyWithMaxLen

src/mongo_logger.ts:474–603

(
  value: any,
  maxDocumentLength: number,
  options: EJSONOptions = {}
)

  | Binary;
/** @internal */
export function stringifyWithMaxLen(
  value: any,
  maxDocumentLength: number,
  options: EJSONOptions = {}
): string {
  let strToTruncate = '';

  let currentLength = 0;
  const maxDocumentLengthEnsurer = function maxDocumentLengthEnsurer(key: string, value: any) {
    if (currentLength >= maxDocumentLength) {
      return undefined;
    }
    // Account for root document
    if (key === '') {
      // Account for starting brace
      currentLength += 1;
      return value;
    }

    // +4 accounts for 2 quotation marks, colon and comma after value
    // Note that this potentially undercounts since it does not account for escape sequences which
    // will have an additional backslash added to them once passed through JSON.stringify.
    currentLength += key.length + 4;

    if (value == null) return value;

    switch (typeof value) {
      case 'string':
        // +2 accounts for quotes
        // Note that this potentially undercounts similarly to the key length calculation
        currentLength += value.length + 2;
        break;
      case 'number':
      case 'bigint':
        currentLength += String(value).length;
        break;
      case 'boolean':
        currentLength += value ? 4 : 5;
        break;
      case 'object':
        if (isUint8Array(value)) {
          // '{"$binary":{"base64":"<base64 string>","subType":"XX"}}'
          // This is an estimate based on the fact that the base64 is approximately 1.33x the length of
          // the actual binary sequence https://en.wikipedia.org/wiki/Base64
          currentLength += (22 + value.byteLength + value.byteLength * 0.33 + 18) | 0;
        } else if ('_bsontype' in value) {
          const v = value as BSONObject;
          switch (v._bsontype) {
            case 'Int32':
              currentLength += String(v.value).length;
              break;
            case 'Double':
              // Account for representing integers as <value>.0
              currentLength +=
                (v.value | 0) === v.value ? String(v.value).length + 2 : String(v.value).length;
              break;
            case 'Long':
              currentLength += v.toString().length;