工具方法

串行执行异步任务

const serialExecute = async (tasks = []) => {
  const resultList = [];
  for (task of tasks) {
    try {
      resultList.push(await task());
    } catch (e) {
      resultList.push(null);
    }
  }
  return resultList;
};

并行执行异步任务

const concurrentExecute = async (tasks = []) => {
  const resultList = await Promise.all(tasks.map((task) => task()));
  return resultList;
};

延迟函数

function sleep(time) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve();
    }, time);
  });
}

生成随机字符串

function randomString(length) {
  // 不能输入   %&\
  // 可以输出  /!@#$^*()_+|?
  let chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
  let result = "";
  for (var i = length; i > 0; --i) result += chars[Math.floor(Math.random() * chars.length)];
  return result;
}

打乱数组

function shuffle(arr) {
  let len = arr.length;
  while (len) {
    let idx = parseInt(Math.random() * len);
    [arr[len - 1], arr[idx]] = [arr[idx], arr[len - 1]];
    len--;
  }
  return arr;
}

追加零

function pad(num) {
   // 0 0 
   // 1 001
  if (num == 0) return 0;
  if (num < 10) return "00" + num;
  if (num < 100) return "0" + num;
  return num;
}

创建目录

function mkdir(dir) {
  fs.mkdir(dir, function (err) {
    if (!err) {
      console.log(green("创建目录: "), dir);
    }
  });
}

下载图片

const downloadImg = async (src, dir) => {
  console.log(dir);
  if (/^data:(.+?);base64,(.+)$/.test(src)) {
    await base64ToImg(src, dir);
  } else {
    await urlToImg(src, dir);
  }
};

const urlToImg = (url, file) => {
  const mod = /^https:/.test(url) ? https : http;
  const dir = path.dirname(file);
  fs.mkdir(dir, function (err) {
    if (!err) {
      console.log("成功创建" + dir + "目录");
    }
  });
  mod.get(url, (res) => {
    res.pipe(fs.createWriteStream(file)).on("finish", () => {
      console.log(file + "下载成功");
    });
  });
};

const base64ToImg = async function (base64Str, file) {
  try {
    const matches = base64Str.match(/^data:(.+?);base64,(.+)$/);
    const dir = path.dirname(file);
    fs.mkdir(dir, function (err) {
      if (!err) {
        console.log("成功创建" + dir + "目录");
      }
    });
    const content = matches[2];
    await fs.writeFile(file, content, "base64");
    console.log(file + " 下载成功");
  } catch (e) {
    console.log(e);
  }
};

获取主机网络地址

const os = require("os");
function getNetworkIp() {
  let hosts = []; // 打开的host
  try {
    // 获得网络接口列表
    let network = os.networkInterfaces();
    for (let dev in network) {
      let iface = network[dev];
      for (let i = 0; i < iface.length; i++) {
        let alias = iface[i];
        if (alias.family === "IPv4" && alias.address !== "127.0.0.1") {
          hosts.push(alias.address);
        }
      }
    }
  } catch (e) {
    hosts.push("localhost");
  }
  return hosts;
}

获取 UserAgent

async function getPuppeteerChromeUA() {
  const browser = await puppeteer.launch();
  const ua = await browser.userAgent();
  await browser.close();
  return ua;
}