SOURCE

function replaceString(a, b) {
  const regex = new RegExp(a, 'g');
  const result = b.replace(regex, '0');
  return result;
}

const a = 'a++['.replace(/[.*+?^${}()|\[\]\\]/g, '\\$&')
const b = 'Thisa++this';
const replacedString = replaceString(a, b);

console.log(replacedString);

// function makeAsyncRequest(url) {
//   return new Promise((resolve, reject) => {
//     // 异步请求的逻辑，例如使用fetch或XMLHttpRequest发送请求
//     // 这里使用setTimeout模拟异步请求
//     setTimeout(() => {
//       resolve(`请求成功: ${url}`);
//     }, Math.random() * 3000);
//   });
// }

// function makeConcurrentRequests(urls, concurrent) {
//   const results = [];
//   const requests = urls.map(url => makeAsyncRequest(url));

//   return new Promise((resolve, reject) => {
//     let index = 0;

//     function sendRequest() {
//       if (index >= urls.length) {
//         resolve(results);
//         return;
//       }

//       const currentUrl = urls[index];
//       const currentRequest = makeAsyncRequest(currentUrl);

//       currentRequest
//         .then(result => {
//           results.push(result);
//         })
//         .catch(error => {
//           console.error(`请求失败: ${currentUrl}`, error);
//         })
//         .finally(() => {
//           index++;

//           if (index < urls.length) {
//             sendRequest();
//           }
//         });

//       index++;
//     }

//     for (let i = 0; i < concurrent; i++) {
//       sendRequest();
//     }
//   });
// }

// const urls = ['url1', 'url2', 'url3', 'url4', 'url5', 'url6', 'url7']; // 异步请求的URL数组
// const concurrentRequests = 3; // 并发请求数量

// makeConcurrentRequests(urls, concurrentRequests)
//   .then(results => {
//     console.log(results);
//   })
//   .catch(error => {
//     console.error(error);
//   });

// const add = (str1, str2) => {
//     let carry = 0
//     let i = str1.length - 1
//     let j = str2.length - 1
//     let result = ''
//     while (i >= 0 || j >= 0 || carry > 0) {
//         const curSum = Number(i >= 0 ? str1[i] : 0) + Number(j >= 0 ? str2[j] : 0) + carry
//         const curLeft = curSum % 10
//         result = curLeft + result
//         carry = Math.floor(curSum / 10)
//         i--
//         j--
//     }
//     return result
// }

// const a = add('12345678901234567890', '98765432109876543210')
// console.log('aaa', a)


// const btn = document.querySelector('.btn')
// btn.addEventListener('click', () => {
//     const a = performance.getEntries()
//     // const a = performance.getEntriesByName('largest-contentful-paint');
//     console.log('aa', a);
//     new PerformanceObserver((entryList) => {
//         const entries = entryList.getEntries();
//         const entry = entries[entries.length - 1];
//         console.log('lcp', entry, entries);
//     }).observe({ type: 'largest-contentful-paint', buffered: true });

//     // const form = new FormData()
//     // form.append('a', 2)
//     // // window.location.replace('https://www.baidu.com/s?ie=UTF-8&wd=%E5%8D%95%E9%A1%B5%E5%BA%94%E7%94%A8%E7%9A%84sendBeaconm')
//     // navigator.sendBeacon('/aaa', form)
// })

// setTimeout(() => {
//     window.location.replace('https://www.baidu.com/s?ie=UTF-8&wd=%E5%8D%95%E9%A1%B5%E5%BA%94%E7%94%A8%E7%9A%84sendBeaconm')
//     navigator.sendBeacon('/aaa')
// }, 3000)

<div class="con">
    <div class="btn">aa</div>
    <!-- <div class="btn2">bb</div> -->
</div>

.con {
    width: 200px;
    height: 200px;
    background: grey;
    position: relative;
    overflow: auto;
}
.btn1 {
    /* background: red; */
    height: 1500px;
    border: 50px solid yellow;
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    z-index: 1;
}
/* .btn2 {
    /* background: red; */
    height: 190px;
    border: 5px solid yellow;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 2;
} */