javascript一些杂的东西_js声明的一些杂点-优快云博客

本文链接：https://blog.youkuaiyun.com/tinfengyee/article/details/99627383

本文介绍了前端开发中常见的时间格式化方法，探讨了未传值时的undefined问题及解决方案，展示了如何获取数组中的最大ID，并提到了在不同浏览器环境下crypto-js的使用注意事项。

格式化时间

Date.prototype.Format = function (fmt) {
    var o = {
            "M+": this.getMonth() + 1, // 月份
            "d+": this.getDate(), // 日
            "h+": this.getHours(), // 小时
            "m+": this.getMinutes(), // 分
            "s+": this.getSeconds(), // 秒
            "q+": Math.floor((this.getMonth() + 3) / 3), // 季度
            "S": this.getMilliseconds() // 毫秒
    };
    if (/(y+)/.test(fmt))
        fmt = fmt.replace(RegExp.$1, (this.getFullYear() + ""));
    for (var k in o)
        if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
    return fmt;
}
new Date(1542274800000).Format('hh:mm:ss'); //"2018-11-15 17:40:00"

关于前端没传值导致undefine问题

const params = {id, status, title} = req.query

这样接收变量, 没有收到的值会自动省略掉

原先就用 if 或者三元表达式逐个接收

遍历最大值ID
let maxId = Math.max.apply(Math, this.keyers.map(item => item.id))

crypto-js使用的一些问题
https://github.com/brix/crypto-js/issues/199

Throughout a few weeks I found that there are some catches:

crypto is not supported on non-trusted websites in Chrome (all SSL addresses + localhost and 127.0.0.1 are supported, but if you're developing a WebView app for Android, then you may have some issues).
Old Microsoft browsers use window.msCrypto instead of window.crypto, so a simple fix for that is defining const Crypto = window.crypto || (window as any).msCrypto;
Also, Microsoft's browsers don't treat TypedArrays, i.e. Uint8Array as... arrays ? So if you would like to perform .reduce() operation on the fresh result of Crypto.getRandomValues(new Uint8Array(96)) (i.e. to output it as string) then you'll have to use a regular loop instead of reduce

常用工具类封装
https://github.com/Baidu-AIP/nodejs-sdk

测代码时间

console.time('console');
console.log('test');
console.timeEnd('console');