var express = require('express')
var app = express();
var allowCrossDomain = function(req, res, next) {//设置response头部的中间件
res.header('Access-Control-Allow-Origin', 'http://localhost:8089');//8089是vue项目的端口，这里相对于白名单
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
res.header('Access-Control-Allow-Headers', 'Content-Type');
res.header('Access-Control-Allow-Credentials','true');
next();
};
app.use(allowCrossDomain);
app.get("/api/data",function (request,response) {
var data = require('./grid.json');//要获取的json文件
response.send(data);
})
app.listen('3000',function () {
console.log('>listening on 3000')
});

fetch( "http://localhost:3000/api/data")
.then(res=>res.json())
.then(data=>console.log(data))
.catch(function (e) {
console.log('oops! error:',e.message)
})