All files / util/src/json-size json.ts

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import {utf8Size} from '../strings/utf8';
 
const numberSize = (num: number) => {
  const isInteger = num === Math.round(num);
  if (isInteger) return Math.max(Math.floor(Math.log10(Math.abs(num))), 0) + 1 + (num < 0 ? 1 : 0);
  return JSON.stringify(num).length;
};
 
const stringSize = (str: string) => {
  const strLength = str.length;
  let byteLength = strLength;
  let pos = 0;
  while (pos < strLength) {
    const value = str.charCodeAt(pos++);
    if (value < 128) {
      switch (value) {
        case 8: // \b
        case 9: // \t
        case 10: // \n
        case 12: // \f
        case 13: // \r
        case 34: // \"
        case 92: // \\
          byteLength += 1;
          break;
      }
      // biome-ignore lint: keep this continue
      continue;
    } else return utf8Size(JSON.stringify(str));
  }
  return byteLength + 2;
};
 
const booleanSize = (bool: boolean) => (bool ? 4 : 5);
 
const arraySize = (arr: unknown[]) => {
  let size = 0;
  const length = arr.length;
  for (let i = 0; i < length; i++) size += jsonSize(arr[i]);
  return size + 2 + (length > 1 ? length - 1 : 0);
};
 
const objectSize = (obj: Record<string, unknown>) => {
  let size = 2;
  let length = 0;
  for (const key in obj)
    if (
      // biome-ignore lint: .hasOwnProperty access is intentional
      obj.hasOwnProperty(key)
    ) {
      length++;
      size += stringSize(key) + jsonSize(obj[key]);
    }
  const colonSize = length;
  const commaSize = length > 1 ? length - 1 : 0;
  return size + colonSize + commaSize;
};
 
/**
 * Computes exact prices JSON size as would be output from JSON.stringify().
 *
 * @param value JSON value to approximate size of
 * @returns Size in bytes of JSON value
 */
export const jsonSize = (value: unknown): number => {
  if (value === null) return 4;
  switch (typeof value) {
    case 'number':
      return numberSize(value);
    case 'string':
      return stringSize(value);
    case 'boolean':
      return booleanSize(value);
  }
  if (value instanceof Array) return arraySize(value);
  return objectSize(value as Record<string, unknown>);
};
 
/**
 * Same as `jsonSize` function, but approximates the size of strings to improve performance.
 * Uses `.length` property of strings to approximate their size.
 *
 * @param value JSON value to approximate size of
 * @returns Size in bytes of JSON value
 */
export const jsonSizeApprox = (value: unknown): number => {
  if (value === null) return 4;
  switch (typeof value) {
    case 'number':
      return numberSize(value);
    case 'string':
      return value.length;
    case 'boolean':
      return booleanSize(value);
  }
  if (value instanceof Array) return arraySize(value);
  return objectSize(value as Record<string, unknown>);
};