看着字面意思，说我的项目（项目名client）没有启用 JavaScript ，莫名其妙完全不能理解。于是乎仔细比对控制台 responses headers 和request headers ，发现了一些猫腻，请求头的 accept 和响应头的 content-type 对不上，请求 css 文件请求头的 accept 是text/css，响应头的 content-type 是 text/html。这个不应该请求什么响应什么吗，我想要崔莺莺一样女子做老婆，给我个杜十娘也认了，结果你给我整个潘金莲让我咋整。
完全不知道到底哪里出了问题，google上面也没有找到方法。开始瞎琢磨，既然对不上，那就想我手动给对上行不行。在express.static 的 setHeaders 里面检查读取文件类型，然后根据文件类型手动设置mime type，我开始佩服我的机智。
app.use( express.static( path.join(process.cwd(), "static"), { maxAge: 0, setHeaders(res，path){ // 通过 path 获取文件类型，设置对应文件的 mime type。 } } ) );
缓存时间设置为0，关掉CDN... 一顿操作, 发现不执行 setHeaders 里面的方法。这个时候已经晚上 11 点了，我已经绝望了，最后一次看了一遍 connect-history-api-fallback 的文档，觉得 htmlAcceptHeaders 这个配置项这么违和，其他的都能明白啥意思，就这个怎么都不能理解，死马当活马医扔进代码试试，居然成了。
const history = require('connect-history-api-fallback') app.use(history({ htmlAcceptHeaders: ['text/html', 'application/xhtml+xml'] rewrites: [ { from: /^\/.*$/, to: function (context) { return "https://www.jb51.net/"; } }, ] }));
到底谁写的文档，静态文件的 headers 的 accepts 和 htmlAcceptHeaders 有什么关系。咱也不知道，咱也没地方问。这事儿耽误了我大半天的时间，不研究透了心里不舒服。老规矩，看 connect-history-api-fallback 源码。
'use strict'; var url = require('url'); exports = module.exports = function historyApiFallback(options) { options = options || {}; var logger = getLogger(options); return function(req, res, next) { var headers = req.headers; if (req.method !== 'GET') { logger( 'Not rewriting', req.method, req.url, 'because the method is not GET.' ); return next(); } else if (!headers || typeof headers.accept !== 'string') { logger( 'Not rewriting', req.method, req.url, 'because the client did not send an HTTP accept header.' ); return next(); } else if (headers.accept.indexOf('application/json') === 0) { logger( 'Not rewriting', req.method, req.url, 'because the client prefers JSON.' ); return next(); } else if (!acceptsHtml(headers.accept, options)) { logger( 'Not rewriting', req.method, req.url, 'because the client does not accept HTML.' ); return next(); } var parsedUrl = url.parse(req.url); var rewriteTarget; options.rewrites = options.rewrites || []; for (var i = 0; i < options.rewrites.length; i++) { var rewrite = options.rewrites[i]; var match = parsedUrl.pathname.match(rewrite.from); if (match !== null) { rewriteTarget = evaluateRewriteRule(parsedUrl, match, rewrite.to, req); if(rewriteTarget.charAt(0) !== 'https://www.jb51.net/') { logger( 'We recommend using an absolute path for the rewrite target.', 'Received a non-absolute rewrite target', rewriteTarget, 'for URL', req.url ); } logger('Rewriting', req.method, req.url, 'to', rewriteTarget); req.url = rewriteTarget; return next(); } } var pathname = parsedUrl.pathname; if (pathname.lastIndexOf('.') > pathname.lastIndexOf('https://www.jb51.net/') && options.disableDotRule !== true) { logger( 'Not rewriting', req.method, req.url, 'because the path includes a dot (.) character.' ); return next(); } rewriteTarget = options.index || '/index.html'; logger('Rewriting', req.method, req.url, 'to', rewriteTarget); req.url = rewriteTarget; next(); }; }; function evaluateRewriteRule(parsedUrl, match, rule, req) { if (typeof rule === 'string') { return rule; } else if (typeof rule !== 'function') { throw new Error('Rewrite rule can only be of type string or function.'); } return rule({ parsedUrl: parsedUrl, match: match, request: req }); } function acceptsHtml(header, options) { options.htmlAcceptHeaders = options.htmlAcceptHeaders || ['text/html', '*/*']; for (var i = 0; i < options.htmlAcceptHeaders.length; i++) { if (header.indexOf(options.htmlAcceptHeaders[i]) !== -1) { return true; } } return false; } function getLogger(options) { if (options && options.logger) { return options.logger; } else if (options && options.verbose) { return console.log.bind(console); } return function(){}; }
这个代码还真是通俗易懂，就不去一行行分析了（其实是我懒）。直接截取关键代码：
else if (!acceptsHtml(headers.accept, options)) { logger( 'Not rewriting', req.method, req.url, 'because the client does not accept HTML.' ); return next(); }