如何把html字符串转成一个React组件？简单而轻量级HTML字符串到React元素转换库htmr React对html支持前景dangerouslySetInnerHTMLreact提供了dangerouslySetInnerHTML属性，把html字符串转成react元素：安全性通常来讲，直接设置dangerouslySetInnerHTML存在风险，因为很容易无意中使用户暴露于跨站脚本(XSS) 的攻击。因此，你可以直接在 React 中设置 HTML，但当你想设置 dangerouslySetInnerHTML 时，需要向其传递包含 key 为 __html 的对象，以此来警示你。正如上面所说，直接使用dangerouslySetInnerHTML存在xss的风险。所以我们需要先对html字符串进行过滤、转换，再通过 React.createElement() 把字符串转成React组件。如果需要自己去实现这一步骤的话，可能会比较麻烦（因为还涉及字符串转dom、属性转React属性等操作）。下面会介绍一个实现这个功能的库htmr和内部原理。htmr安装方法$ yarn add htmr # or $ npm install htmr --save使用htmr接收两个参数，html字符串和一个配置对象options。html：stringoptions：Partial<HtmrOptions>={}下面着重介绍下HtmrOptions里面各个属性：preserveAttributes：Array<String | RegExp> - 默认情况下，htmr会将符合要求的html属性转换为React要求的驼峰式属性，如果某些属性不想转换，可以通过该属性来阻止React这个行为。transform - 接受键值对，这些键值对将用于 将节点（键）转换为自定义组件（值），可以使用它来通过自定义组件呈现特定的标签名称。例如，下面这个例子。定义了transform对象，目的是把p标签转成Paragraph组件，把a标签转成span标签：const transform = { p: Paragraph, a: 'span' } htmr('<p><a>Hello, world!</a></p>', {transform}) // 结果 => <Paragraph><span>Custom component</span></Paragraph>在 transform 里面有一个参数叫做defaultTransform, 以符号 _表示，它接受的参数跟React.createElement一致。这个参数非常有用，例如可以在富文本里面处理图片，把图片转成我们自定义的图片组件const transform = { // 参数跟React.createElement一致 _: (nodeName, props, children) => { if(nodeName === 'img) { let src = props.src; return <Image src={src}> } return React.createElement(nodeName, props, children); } }在 transform 里面还有一个参数叫 dangerouslySetChildren ，出于安全原因，默认情况下，htmr仅将危险标签内的样式标记的子项呈现在危险地设置为InnerHTML中。例如，下面例子设置dangerouslySetChildren：['code']：const html = '<div><code><span>xxx</span></code></div>' htmr(html, { dangerouslySetChildren: ['code'] }); // <div><code dangerouslySetInnerHTML={{__html: encode('<span>xxx</span>')}}>工具函数hypenColonToCamelCase把带中划线或者冒号的字符串转成驼峰式，如 color-profile => colorProfile，xlink:role => xlinkRole 。function hypenColonToCamelCase(str: string): string { return str.replace(/(-|:)(.)/g, (match, symbol, char) => { return char.toUpperCase(); }); }convertValuefunction convertValue(value: string): number | string { if (/^\d+$/.test(value)) { return Number(value); } return value.replace(/'/g, '"'); }convertStyle把行内样式字符串转成StyleObject类型：function convertStyle(styleStr: string): StyleObject { const style = {} as StyleObject; styleStr .split(';') .filter(style => style.trim() !== '') .forEach(declaration => { const rules = declaration.split(':'); if (rules.length > 1) { // 属性名 const prop = hypenColonToCamelCase(rules[0].trim()); const val = convertValue( rules .slice(1) .join(':') .trim() ); style[prop] = val; } }); return style; }内部原理htmlServer我们在上面例子用到的htmr函数其实就是htmlServer，它主要做了两件事情：html字符串转成dom；对dom所有节点做转换成符合要求的ReactElement；export default function htmrServer( html: string, options: Partial<HtmrOptions> = {} ) { if (typeof html !== 'string') { throw new TypeError('Expected HTML string'); } const doc = parseDocument(html.trim(), {}); // 1. const nodes = doc.childNodes.map((node, index) => // 2. toReactNode(node, index.toString(), options) ); return nodes.length === 1 ? nodes[0] : nodes; }htmlServer用到一个parseDocument方法，它是 htmlparser2导出的一个函数，能把html字符串转化成dom：import { parseDocument } from 'htmlparser2';toReactNode顾名思义，toReactNode是把dom转成ReactNode，也是这个库的核心。根据dom节点的type属性，做了分类处理：如果type 的值是 'script' 、'style' 和 'tag' 其中之一，执行如下操作：解码所有属性值；执行mapAttribute（把属性转成React属性）；根据transform转化标签；const node: HTMLNode = childNode as any; const { name, attribs } = node; // decode all attribute value Object.keys(attribs).forEach((key) => { attribs[key] = decode(attribs[key]); }); const props = Object.assign( {}, mapAttribute(name, attribs, preserveAttributes, getPropName), { key } ); /** * const transform = { * p: Paragraph, * a: 'span', * }; * 例如把 p标签转成 Paragraph标签，a转成span */ const customElement = transform[name];判断当前标签是否在dangerouslySetChildren列表，是的话塞到dangerouslySetInnerHTMLif (dangerouslySetChildren.indexOf(name) > -1) { // Tag can have empty children if (node.children.length > 0) { const childNode: TextNode = node.children[0] as any; const html = name === 'style' || name === 'script' ? // preserve encoding on style & script tag childNode.data.trim() : encode(childNode.data.trim()); props.dangerouslySetInnerHTML = { __html: html }; } return customElement ? React.createElement(customElement as any, props, null) : defaultTransform ? defaultTransform(name, props, null) : React.createElement(name, props, null); }对children节点执行toReactNode；如果存在transform，转化成对应ReactElement并返回；如果存在defaultTransform ，调用defaultTransform 并返回；如果不存在transform和defaultTransform，执行React.createElement；// 5. const childNodes = node.children .map((node, index) => toReactNode(node, index.toString(), options)) .filter(Boolean); // self closing component doesn't have children const children = childNodes.length === 0 ? null : childNodes; // 6. if (customElement) { return React.createElement(customElement as any, props, children); } // 7. if (defaultTransform) { return defaultTransform(name, props, children); } // 8. return React.createElement(name, props, children);如果type是'text',则处理很简单：const node: TextNode = childNode as any; let str = node.data; if (node.parent && TABLE_ELEMENTS.indexOf(node.parent.name) > -1) { str = str.trim(); if (str === '') { return null; } } str = decode(str); return defaultTransform ? defaultTransform(str) : str;接下来，了解一下第2步提到的mapAttribute是如何把html属性转成React属性的。mapAttribute首先，先贴上代码：Object.keys(attrs).reduce((result, attr) => { // 1 if (/^on.*/.test(attr)) { return result; } // 2 let attributeName = attr; if (!/^(data|aria)-/.test(attr)) { // Allow preserving non-standard attribute, e.g: `ng-if` const preserved = preserveAttributes.filter(at => { if (at instanceof RegExp) { return at.test(attr); } return at === attr; }); if (preserved.length === 0) { attributeName = hypenColonToCamelCase(attr); } } // 3 const name = getPropName(originalTag, attributeName); // 4 if (name === 'style') { result[name] = convertStyle(attrs.style!); } // 5 else { const value = attrs[attr] const isBooleanAttribute = value === '' || String(value).toLowerCase() === attributeName.toLowerCase(); result[name] = isBooleanAttribute ? true : value; } return result; }从代码分析：通过正则 /^on.*/.test(attr) 判断是否内联事件，如果是则忽略掉（所有内联事件都不会生效）。转化除了 data-和aria- 并且不在preserveAttributes 数组内的属性成驼峰式。把html属性转化为符合React规范的属性，具体如何转化的下面提供了一个JSON文件：{ "for": "htmlFor", "class": "className", "acceptcharset": "acceptCharset", "accesskey": "accessKey", "allowfullscreen": "allowFullScreen", "autocomplete": "autoComplete", "autofocus": "autoFocus", "autoplay": "autoPlay", "cellpadding": "cellPadding", "cellspacing": "cellSpacing", "charset": "charSet", "classid": "classID", "classname": "className", "colspan": "colSpan", "contenteditable": "contentEditable", "contextmenu": "contextMenu", "crossorigin": "crossOrigin", "datetime": "dateTime", "enctype": "encType", "formaction": "formAction", "formenctype": "formEncType", "formmethod": "formMethod", "formnovalidate": "formNoValidate", "formtarget": "formTarget", "frameborder": "frameBorder", "hreflang": "hrefLang", "htmlfor": "htmlFor", "httpequiv": "httpEquiv", "inputmode": "inputMode", "keyparams": "keyParams", "keytype": "keyType", "marginheight": "marginHeight", "marginwidth": "marginWidth", "maxlength": "maxLength", "mediagroup": "mediaGroup", "minlength": "minLength", "novalidate": "noValidate", "radiogroup": "radioGroup", "readonly": "readOnly", "rowspan": "rowSpan", "spellcheck": "spellCheck", "srcdoc": "srcDoc", "srclang": "srcLang", "srcset": "srcSet", "tabindex": "tabIndex", "usemap": "useMap", "viewbox": "viewBox" }转行内样式成StyleObject；转化布尔属性什么是布尔属性❓总结htmr内部对html字符串进行dom转换，接着递归遍历所有节点，对节点（和属性）过滤、转换，再通过React.createElement()把字符串转成React组件。作者：路一直在_走链接：https://www.jianshu.com/p/36639da716e7来源：简书著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

ADODB.Connection 错误 800a0e7a 未找到提供程序。该程序可能未正确安装解决方法 很久没有处理ASP网站，最近有个老网站换服务器需要处理一下，老网站的服务器已经处于无法打开的情况，换上去后报错，原来是很久以前解决过的问题，但是已经忘记了，解决后做个备忘录，防止下次再出问题。 Windows2008系统 IIS7.5 调试ASP(aspcmsgbk25) 错误号：3706 提示 “未找到提供程序 该程序可能未正确安装”解决办法 有两种报错形式一、错误号：3706 错误描述：未找到提供程序。该程序可能未正确安装。二、“ADODB.Connection 错误 '800a0e7a' 未找到提供程序。该程序可能未正确安装。 ”错误的原因在于在64位系统中，IIS7应用程序池默认没有启用32位程序，也就是说如果使用的是64位操作系统，而没有64位的Jet 4.0驱动程序，那么就要在IIS7中启用32位程序。解决方法如下：Internet信息服务(IIS)管理器 - ‘应用程序池’ - 右边操作中选择‘设置应用程序池默认设置..’，在‘常规’中设置‘启用 32 位程序’为True。如下图：

C#插件火车头采集器动态切换代理IP，及自动切换UserAgent 通过代理供应商接口，实时获取代理IP，每个IP使用1分钟，1分钟后重新获取新IP。整合网上抄来的随机UserAgent，合成了一个火车头插件。using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Text.RegularExpressions; using SpiderInterface; using System.Net; using System.IO; namespace PluginSample { public class Plugin1 : IHTTPTamper { string[] agentList =new string[] { "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36 OPR/26.0.1656.60", "Opera/8.0 (Windows NT 5.1; U; en)", "Mozilla/5.0 (Windows NT 5.1; U; en; rv:1.8.1) Gecko/20061208 Firefox/2.0.0 Opera 9.50", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 9.50", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0", "Mozilla/5.0 (X11; U; Linux x86_64; zh-CN; rv:1.9.2.10) Gecko/20100922 Ubuntu/10.10 (maverick) Firefox/3.6.10", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.57.2 (KHTML, like Gecko) Version/5.1.7 Safari/534.57.2", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11", "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.133 Safari/534.16", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.101 Safari/537.36", "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.11 TaoBrowser/2.0 Safari/536.11", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.71 Safari/537.1 LBBROWSER", "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; LBBROWSER)", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E; LBBROWSER)", "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; QQBrowser/7.0.3698.400)", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E)", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.84 Safari/535.11 SE 2.X MetaSr 1.0", "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SV1; QQDownload 732; .NET4.0C; .NET4.0E; SE 2.X MetaSr 1.0)", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Maxthon/4.4.3.4000 Chrome/30.0.1599.101 Safari/537.36", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 UBrowser/4.0.3214.0 Safari/537.36" }; public void CheckCacheDir() { string Dir = "D:\\IPCACHE\\"; if (!Directory.Exists(Dir)) Directory.CreateDirectory(Dir); } public string GetUrlContent(string url) { using(WebClient wc = new WebClient()){ try { return Encoding.GetEncoding("UTF-8").GetString(wc.DownloadData(string.Format(url))); } catch (Exception e) { throw new Exception(e.ToString()); } } } public string ReadTxt() { string Result = ""; try { string filename = "D:\\IPCACHE\\" + DateTime.Now.ToString("yyyyMMddHHmm") + ".txt"; using (StreamReader sr = new StreamReader(filename)) { Result = sr.ReadToEnd(); } } catch { Result = "缓存不存在"; } return Result; } public string WriteTxt(string val) { try { string filename = "D:\\IPCACHE\\" + DateTime.Now.ToString("yyyyMMddHHmm") + ".txt"; using (StreamWriter sr = new StreamWriter(filename)) { sr.Write(val); } } catch { return "fail"; } return "Success"; } public string GetProxyIp(){ string ProxyApi = "代理IP获取的API, 结果应该是 0.0.0.0.0:xxxx"; CheckCacheDir(); string ip = ""; //检查缓存 string ProxyCache = ReadTxt(); if (ProxyCache != "缓存不存在" && ProxyCache != "") { ip = ProxyCache; } else { ip = GetUrlContent(ProxyApi); WriteTxt(ip); } return ip; } /// <summary> /// 处理下载前的request /// </summary> /// <param name="response"></param> public void BeforeRequest(RequestEntry request) { //Console.WriteLine("BeforeRequest："+request.Url); //request.Referer=""; //request.Headers. Random r = new Random(); string Agent = agentList[r.Next(agentList.Length)]; request.Headers["User-Agent"] =Agent; var proxy = new WebProxy(GetProxyIp(), true); request.WebProxy=proxy; } /// <summary> /// 处理下载完成后的http响应,网址、默认页、多页、内容分页 /// </summary> /// <param name="response"></param> public void AfterResponse(ResponseEntry response) { Console.WriteLine("AfterResponse：" + response.Url); } } }

sql 中的 indexOf 与 lastIndexOf DECLARE @Name NVARCHAR (50) SET @Name = ‘12345.67890ABCDE.FGHIJKLMNOPQRSTUVWXYZTest’ DECLARE @Position INT –sql first indexof SET @Position = CHARINDEX(‘.’, @Name); SELECT SUBSTRING (@Name, @Position+1,LEN(@Name)-@Position) –sql last indexof SET @Position = LEN(@Name) – CHARINDEX(‘.’, REVERSE(@Name)) + 1 SELECT SUBSTRING (@Name, 0, @Position)

快速删除node_modules文件夹 前言当安装了较多模块后，node_modules目录下的文件会很多，直接删除整个目录会很慢，下面介绍些快速删除node_modules目录的方法。方法一：使用rimraf模块的命令在全局安装rimraf模块，然后通过其命令来快速删除node_modules目录：npm install rimraf -g rimraf node_modules方法二：使用命令来删除目录Windows下使用rmdir命令 首先在cmd窗口中进入到node_modules文件夹所在的路径，接着执行命令：rmdir /s/q node_modules Linux下使用rm命令 rm -f /node_modules