前言

做前端有时会采用一些复杂框架,在文件系统中直接打开页面(用file:///方式打开),往往会报跨域的错,类似于“XMLHttpRequest cannot load …(文件名). Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https, chrome-extension-resource.”。这时,我们可以快速搭建一个简单的静态文件服务器,用Node.js最合适。

1.在前端项目根目录下创建server.js,代码如下:

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"use strict";
//加载所需要的模块
var http = require('http');
var url = require('url');
var fs = require('fs');
var path = require('path');
var cp = require('child_process');

//创建服务
var httpServer = http.createServer(processRequest);

var port = 8080;

//指定一个监听的接口
httpServer.listen(port, function() {
console.log(`app is running at port:${port}`);
console.log(`url: http://localhost:${port}`);
cp.exec(`explorer http://localhost:${port}`, function () {
});
});

//响应请求的函数
function processRequest (request, response) {
//mime类型
var mime = {
"css": "text/css",
"gif": "image/gif",
"html": "text/html",
"ico": "image/x-icon",
"jpeg": "image/jpeg",
"jpg": "image/jpeg",
"js": "text/javascript",
"json": "application/json",
"pdf": "application/pdf",
"png": "image/png",
"svg": "image/svg+xml",
"swf": "application/x-shockwave-flash",
"tiff": "image/tiff",
"txt": "text/plain",
"wav": "audio/x-wav",
"wma": "audio/x-ms-wma",
"wmv": "video/x-ms-wmv",
"xml": "text/xml"
};

//request里面切出标识符字符串
var requestUrl = request.url;
//url模块的parse方法 接受一个字符串,返回一个url对象,切出来路径
var pathName = url.parse(requestUrl).pathname;

//对路径解码,防止中文乱码
var pathName = decodeURI(pathName);

//解决301重定向问题,如果pathname没以/结尾,并且没有扩展名
if (!pathName.endsWith('/') && path.extname(pathName) === '') {
pathName += '/';
var redirect = "http://" + request.headers.host + pathName;
response.writeHead(301, {
location: redirect
});
//response.end方法用来回应完成后关闭本次对话,也可以写入HTTP回应的具体内容。
response.end();
}

//获取资源文件的绝对路径
var filePath = path.resolve(__dirname + pathName);
console.log(filePath);
//获取对应文件的文档类型
//我们通过path.extname来获取文件的后缀名。由于extname返回值包含”.”,所以通过slice方法来剔除掉”.”,
//对于没有后缀名的文件,我们一律认为是unknown。
var ext = path.extname(pathName);
ext = ext ? ext.slice(1) : 'unknown';

//未知的类型一律用"text/plain"类型
var contentType = mime[ext] || "text/plain";

fs.stat(filePath, (err, stats) => {
if (err) {
response.writeHead(404, { "content-type": "text/html" });
response.end("<h1>404 Not Found</h1>");
}
//没出错 并且文件存在
if (!err && stats.isFile()) {
readFile(filePath, contentType);
}
//如果路径是目录
if (!err && stats.isDirectory()) {
var html = "<head><meta charset = 'utf-8'/></head><body><ul>";
//读取该路径下文件
fs.readdir(filePath, (err, files) => {
if (err) {
console.log("读取路径失败!");
} else {
//做成一个链接表,方便用户访问
var flag = false;
for (var file of files) {
//如果在目录下找到index.html,直接读取这个文件
if (file === "index.html") {
readFile(filePath + (filePath[filePath.length-1]=='/' ? '' : '/') + 'index.html', "text/html");
flag = true;
break;
};
html += `<li><a href='${file}'>${file}</a></li>`;
}
if(!flag) {
html += '</ul></body>';
response.writeHead(200, { "content-type": "text/html" });
response.end(html);
}
}
});
}

//读取文件的函数
function readFile(filePath, contentType){
response.writeHead(200, { "content-type": contentType });
//建立流对象,读文件
var stream = fs.createReadStream(filePath);
//错误处理
stream.on('error', function() {
response.writeHead(500, { "content-type": contentType });
response.end("<h1>500 Server Error</h1>");
});
//读取文件
stream.pipe(response);
}
});
}

2.在前端项目根目录下打开命令提示符或终端,输入以下命令就可以启动小服务器啦。

1
node server.js