socket.io/lib/util.ts

import { globalThisShim as globalThis } from "./globals.node.js";

export function pick(obj, ...attr) {
  return attr.reduce((acc, k) => {
    if (obj.hasOwnProperty(k)) {
      acc[k] = obj[k];
    }
    return acc;
  }, {});
}

// Keep a reference to the real timeout functions so they can be used when overridden
const NATIVE_SET_TIMEOUT = globalThis.setTimeout;
const NATIVE_CLEAR_TIMEOUT = globalThis.clearTimeout;

export function installTimerFunctions(obj, opts) {
  if (opts.useNativeTimers) {
    obj.setTimeoutFn = NATIVE_SET_TIMEOUT.bind(globalThis);
    obj.clearTimeoutFn = NATIVE_CLEAR_TIMEOUT.bind(globalThis);
  } else {
    obj.setTimeoutFn = globalThis.setTimeout.bind(globalThis);
    obj.clearTimeoutFn = globalThis.clearTimeout.bind(globalThis);
  }
}

// base64 encoded buffers are about 33% bigger (https://en.wikipedia.org/wiki/Base64)
const BASE64_OVERHEAD = 1.33;

// we could also have used `new Blob([obj]).size`, but it isn't supported in IE9
export function byteLength(obj) {
  if (typeof obj === "string") {
    return utf8Length(obj);
  }
  // arraybuffer or blob
  return Math.ceil((obj.byteLength || obj.size) * BASE64_OVERHEAD);
}

function utf8Length(str) {
  let c = 0,
    length = 0;
  for (let i = 0, l = str.length; i < l; i++) {
    c = str.charCodeAt(i);
    if (c < 0x80) {
      length += 1;
    } else if (c < 0x800) {
      length += 2;
    } else if (c < 0xd800 || c >= 0xe000) {
      length += 3;
    } else {
      i++;
      length += 4;
    }
  }
  return length;
}

/**
 * Generates a random 8-characters string.
 */
export function randomString() {
  return (
    Date.now().toString(36).substring(3) +
    Math.random().toString(36).substring(2, 5)
  );
}