拼多多3.12 前端笔试 代码题
笔试的时候写的3题都跑不起来。。一堆错误，整理了下能跑的版本
(不保证是对的
第一题：
<body>
<div id="welcome"></div>
</body>
<script>
function generateAndInsertContent() {
const beginTime = new Date('2023-1-1').getTime();
const endTime = new Date('2024-1-1').getTime() - (24 * 60 * 60 * 1000);
const halfYear = 180 * 24 * 60 * 60 * 1000;
const today = new Date();
let todayTime = today.getTime();
const dayNums = Math.floor((todayTime - beginTime) / (1000 * 60 * 60 * 24));
let str = `今天是${today.getUTCFullYear()}年的第<span style=\"color:red;\">${dayNums}<\/span>天，`;
if(todayTime - beginTime <= halfYear) {
str += '你好，上半年！';
} else if(todayTime - beginTime > endTime && todayTime - beginTime < (new Date('2024-1-1').getTime())) {
str += '明年见！';
} else {
str += `再见了，上半年！你好，下半年！`;
}
document.getElementById('welcome').innerHTML = str;
}
generateAndInsertContent();
</script>
第二题：
<div id="card" class="card">
<div id="quickBtn" class="quick-btn">quick look</div>
</div>
<script>
function clickCard(e) {
alert('card click');
}
function clickBtn(e) {
e.stopPropagation();
alert('quick look click');
}
const card = document.getElementById('card');
card.addEventListener('click', clickCard);
const btn = document.getElementById('quickBtn');
btn.addEventListener('click', clickBtn);
card.addEventListener('mouseenter', function() {
btn.style.display = 'block';
});
card.addEventListener('mouseleave', function() {
btn.style.display = 'none';
});
</script>
<style>
.card {
position: relative;
width: 256px;
height: 256px;
background-color: #f4f4f4;
}
.quick-btn {
display: none;
text-align: center;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
width: 92px;
height: 27px;
padding: 5px;
font-size: 16px;
background-color: white;
border: 1px solid #ddd;
border-radius: 15px;
}
</style>
第三题：
#笔试复盘##拼多多笔试#
async function preloadImage(imgUrls, timeout) {
let allOk = true; // x秒内是否全部响应完成
await Promise.all(imgUrls.map(imgUrl => requestImage(imgUrl, new Date().getTime()))
.map(item => { // 捕获所有 promise 的 reject，输出加载失败信息
return item.catch(errMsg => {
console.log(errMsg)
})
})).then((reslist) => {
reslist.forEach(costTime => {
if(costTime > timeout) { // 有请求超时了
allOk = false;
}
})
})
if(!allOk) {
console.log(`resource load cost over ${timeout} ms`);
}
}
// 模拟请求单张图片，入参：单个图片url、开始请求的时间
const requestImage = async(imgUrl, beginTime) => new Promise((resolve, reject) => {
if(Math.random() < 0.7) // 一定概率是请求成功的
setTimeout(() => resolve(new Date().getTime() - beginTime), 1000);
else
setTimeout(() => reject(`${imgUrl} load fail`), 1000);
});
preloadImage(['1.png', '2.png', '3.png'], 1002);
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