浏览器访问路径不提示下载而显示新页面应该如何解决

var http = require('http');var fs = require('fs');var url = require('url');var routes = {//<====路由
 "/video"(request, response) {
 fs.readFile("frag_bunny.mp4", 'binary', function (err, data) { if (err) { console.log(err);
 response.writeHead(500, { 'Content-Type': 'text/html' });
 } else {
 response.writeHead(200, { 'Content-Type': 'video/mp4' });//<====mp4标识
 response.write(data, 'binary');
 }
 response.end();
 });
 }, "/frag_bunny.mp4"(request, response) {
 fs.readFile("frag_bunny.mp4", 'binary', function (err, data) { if (err) { console.log(err);
 response.writeHead(500, { 'Content-Type': 'text/html' });
 } else {
 response.writeHead(200, { 'Content-Type': 'application/octet-stream' });//<====文件流标识
 response.write(data, 'binary');
 }
 response.end();
 });
 }, "/"(request, response) {
 response.writeHead(200, { 'Content-Type': 'text/html' }); 
 response.write(`
 <a target= "_blank" href="/video">打开页面显示播放界面</a>
 <br />
 <a target= "_blank" href="/frag_bunny.mp4">打开页面提示下载</a>
 `);
 response.end();
 }, "/404"(request, response) {
 response.writeHead(404, { 'Content-Type': 'text/html' });
 response.write("404");
 response.end();
 }
}// 创建服务器http.createServer(function (request, response) { // 解析请求，包括文件名
 var pathname = url.parse(request.url).pathname; //