NodejsにH 5 Historyモード(connect-history-api-fallbackソースコード解析)をサポートさせる
リード
本文は主に
ソース分析
本文は主に
connect-history-api-fallback
ライブラリに対してソースコード分析を行った.connect-history-api-fallback
は、SPA Historyルーティングモードをサポートするためのnodejs
ライブラリである.本文を読む前に、HTML5 History
モードに対応してある程度の理解があります!ソース分析
/**
* history , url api , localhost:4200/home url, “ html, ”, 。
* , 。
* connect-history-api-fallback , !
* , , !
*/
'use strict';
var url = require('url');
exports = module.exports = function historyApiFallback(options) {
//
options = options || {};
//
var logger = getLogger(options);
// , req, res, next
return function(req, res, next) {
var headers = req.headers;
if (req.method !== 'GET') {
// GET , html, next(),
logger(
'Not rewriting',
req.method,
req.url,
'because the method is not GET.'
);
return next();
} else if (!headers || typeof headers.accept !== 'string') {
// , accept , http , ,
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) {
// application/json , html, ,
logger(
'Not rewriting',
req.method,
req.url,
'because the client prefers JSON.'
);
return next();
} else if (!acceptsHtml(headers.accept, options)) {
// Accept ['text/html', '*/*'], html, ,
logger(
'Not rewriting',
req.method,
req.url,
'because the client does not accept HTML.'
);
return next();
}
// html ,
// url parse url, , protocol,hash,path, pathname, query, search , location
var parsedUrl = url.parse(req.url);
var rewriteTarget;
// rewrites, ;
// , from to ;
// from pathname ;
// to url,to , , context,context (parsedUrl,match,request)
options.rewrites = options.rewrites || [];
//
for (var i = 0; i < options.rewrites.length; i++) {
var rewrite = options.rewrites[i];
// match
var match = parsedUrl.pathname.match(rewrite.from);
if (match !== null) {
// match null, pathname
rewriteTarget = evaluateRewriteRule(parsedUrl, match, rewrite.to, req);
if(rewriteTarget.charAt(0) !== '/') {
// / url
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);
// url
req.url = rewriteTarget;
return next();
}
}
var pathname = parsedUrl.pathname;
// : url . , . , history
// “ ”
// disableDotRule true,
if (pathname.lastIndexOf('.') > pathname.lastIndexOf('/') &&
options.disableDotRule !== true) {
// pathname / ., /a/b/c/d.* (* );
// disableDotRule false, , ,
logger(
'Not rewriting',
req.method,
req.url,
'because the path includes a dot (.) character.'
);
return next();
}
// pathname / ., disableDotRule true, : url
// url /index.html, index
rewriteTarget = options.index || '/index.html';
logger('Rewriting', req.method, req.url, 'to', rewriteTarget);
// url
req.url = rewriteTarget;
// (url index.html , , html , !)
next();
};
};
// to
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.');
}
// , url
return rule({
parsedUrl: parsedUrl,
match: match,
request: req
});
}
// accept
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) {
// , verbose, console.log
return console.log.bind(console);
}
// ,
return function(){};
}