前端两三问(20190915)

1、Js获取当前时间

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function dateFormat(date, format) {
if (!date) {
return ''
}
if (!(date instanceof Date)) {
date = new Date(date)
if (date.toString() === 'Invalid Date') {
return '无效时间戳'
}
}
format = format || 'yyyy-MM-dd hh:mm:ss'
const o = {
"M+": date.getMonth() + 1, //月份
"d+": date.getDate(), //日
"h+": date.getHours(), //小时
"m+": date.getMinutes(), //分
"s+": date.getSeconds(), //秒
"q+": Math.floor((date.getMonth() + 3) / 3), //季度
"S": date.getMilliseconds() //毫秒
};
if (/(y+)/.test(format)) {
format = format.replace(RegExp.$1, (date.getFullYear() + "").substr(4 - RegExp.$1.length));
}
for (const k in o)
if (new RegExp("(" + k + ")").test(format)) {
format = format.replace(RegExp.$1, (RegExp.$1.length === 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
}
return format;
}

console.log(date.Format(new Date(), 'yyyy-MM-dd') // 2019-09-11

2、css 三角形

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.sj {
width: 0;
height: 0;
border-width: 100px;
border-style: solid;
}

.sj-left {
border-color: transparent pink transparent transparent;
}

.sj-right {
border-color: transparent transparent transparent pink;
}

.sj-top {
border-color: transparent transparent pink transparent;
}

.sj-bottom {
border-color: pink transparent transparent transparent;
}

3、js 取并集 交集

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let a = [1,2,3,4,5]
let b = [2,4,6,8,10]

let sa = new Set(a);
let sb = new Set(b);

// 交集
let intersect = a.filter(x => sb.has(x));

// 差集
let minus = a.filter(x => !sb.has(x));

// 补集
let complement = [...a.filter(x => !sb.has(x)), ...b.filter(x => !sa.has(x))];

// 并集
let unionSet = Array.from(new Set([...a, ...b]));

console.log("a与b的交集:", intersect);
console.log("a与b的差集:", minus);
console.log("a与b的补集:", complement);
console.log("a与b的并集:", unionSet);