202307 #

(?<=p) // 符合p子模式后面(注意(?=p)表示的是前面)的那个位置
(?=p) // 符合p子模式前面的那个位置

let str = 'xxx_love'
str.replace(/(?=xxx)/g, 'cpp') // cppxxx_love
str.replace(/(?<=xxx)/g, 'cpp') // xxxcpp_love

const text = "Hello world, my name is John.";

// 使用正则表达式匹配名字
const regex = /name is (\w+)/;
const match = regex.exec(text);

if (match) {
  console.log("整个匹配结果:", match[0]); // "name is John"
  console.log("捕获组 1:", match[1]); // "John"
  console.log("RegExp.$1:", RegExp.$1); // "John"
}

// 前序 根左右
// 进栈 右左
// 出栈 左右
function preOrder(root, res = []) {
  if (!root) return res;
  var queue = [root];
  while (queue.length) {
    var cur = queue.pop();
    res.push(cur.val);
    if (cur.right) queue.push(cur.right);
    if (cur.left) queue.push(cur.left);
  }
  return res;
}

// 后序遍历 左右中
function postOrder(root, res = []) {
  if (!root) return res;
  var queue = [root];
  while (queue.length) {
    var cur = queue.pop();
    res.push(cur.val);
    if (cur.left) queue.push(cur.left);
    if (cur.right) queue.push(cur.right);
  }
  return res.reverse();
}

// 中序 左根右
function inOrder(root, res = []) {
  if (!root) return res;
  var stack = [];
  var cur = root;
  while (stack.length && cur) {
    // 左
    if (cur) {
      stack.push(cur);
      cur = cur.left; //  左
    } else {
      cur = stack.pop(); // 根
      res.push(cur.val);
      cur = cur.right; // 右
    }
  }
}

// 层序
function levelOrder(root, res = []) {
  if (!root) return res;
  var queue = [root];
  while (queue.length) {
    var len = queue.length;
    var arr = [];
    for (let item of queue) {
      var cur = queue.shift();
      arr.push(cur.val);
      if (cur.left) {
        queue.push(cur.left);
      }
      if (cur.right) {
        queue.push(cur.right);
      }
    }
    res.push(arr);
  }
  return res;
}

function jsonpCallback(url, cb) {
  var script = document.createElement("script");
  script.async = true;
  script.href = url + "?cb=" + cb;
  var fnname = cb;
  window[fnname] = function (...rest) {
    cb(rest);
    delete window[fnname];
    document.body.removeChild(script);
  };
  document.body.appendChild(script);
}

function asyncToGenerator(G) {
  return function () {
    const gen = G.apply(this, arguments);
    return new Promise((resolve, reject) => {
      function step(key, ...val) {
        var res = gen[key](val);
        const { done, value } = res;
        try {
          if (done) {
            resolve(value);
          } else {
            return Promise.resolve(value).then(
              (val) => {
                step("next", val);
              },
              (err) => {
                step("throw", err);
              }
            );
          }
        } catch (e) {
          reject(e);
        }
      }
      step("next");
    });
  };
}

// 删除链表一个节点

// 选择排序和插入排序

// 反转链表

// 链表是否有环？

// 手写数字的千分位分割法

const [count, setCount] = useState(0);

useEffect(() => {
  // 添加事件监听
  document.addEventListener("click", handleClick, true);
  return () => {
    // 移除事件监听
    document.removeEventListener("click", handleClick, true);
  };
}, []);

const handleClick = () => {
  // 执行一些读取state的操作
  console.log(count);
  setCount(count + 1);
};
return <h1>{count}</h1>;

const [count, setCount] = useState(0);
const countRef = useRef(0);
useEffect(() => {
  // 添加事件监听
  document.addEventListener("click", handleClick, true);
  return () => {
    // 移除事件监听
    document.removeEventListener("click", handleClick, true);
  };
}, []);

const handleClick = () => {
  // 执行一些读取state的操作
  console.log(countRef.current);
  setCount((count) => count + 1);
};
useEffect(() => {
  countRef.current = count;
}, [count]);
return <h1>{count}</h1>;

  location / {
    proxy_pass http://southgate/mobile; // error
  }
  location / {
    proxy_pass http://southgate/mobile/; // correct
  }

const nextConfig = {
  experimental: {
    appDir: true,
  },
  reactStrictMode: false,
};
module.exports = nextConfig;

<link rel="canonical" href="https://example.com/product-a/" />

  // 跨域调试 next.config.js
  async rewrites() {
    return [
      {
        source: "/app/download/latest",
        destination: `http://m.xx.com/app/download/latest`,
      },
    ];
  },

import Head from "next/head";
function IndexPage() {
  return (
    <div>
      <Head>
        <title>My page title</title>
        <meta property="og:title" content="My page title" key="title" />
      </Head>
      <Head>
        <meta property="og:title" content="My new title" key="title" />
      </Head>
      <p>Hello world!</p>
    </div>
  );
}
export default IndexPage;