Node.Js错误“在请求的服务器上没有'Access-Control-Allow-Origin'标头”。 [英] Node.Js error "No 'Access-Control-Allow-Origin' header is present on the requested"

问题描述

这个问题与其他问题相似；但是有一个区别，使它为什么不起作用非常令人困惑。

This question is similar to others; however there is a difference that makes it very confusing why it is not working.

我的JavaScript调用了6个json文件，并且所有文件都能正常工作。在Node.JS中，我设置了cors和标头，如下所示：

My JavaScript was calling 6 json files and all worked correctly. In Node.JS I have cors and headers set up as shown below:

var fs = require('fs');
var http = require("https");
var express = require('express');
var app = express();
var path = require('path');
var http = require("http");
var url = require("url");
var req = require('request')
var pem = require('pem');
var cors = require("cors");

app.use(express.static(path.join(__dirname, '../')));

app.listen(process.env.PORT || 8080);

app.options('*', cors()); 

app.use(function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-  With, Content-Type, Accept");
    next();   
});

app.all('/posts', function(req, res){
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
});

app.get('/', function (req, res) { 
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept"); 
    res.writeHead(200, {'Content-Type': 'text/plain'});
    contents = fs.readFileSync("sliderImages.json", "utf8");
    console.log(path.join(__dirname, '/sliderImages.json'));
    res.end(contents);
});

所有6个json文件都由Node JS从绝对URL路径中获取。昨天我又赚了2个，一切工作正常。但是，今天我做了一个实现相同的方法，并收到以下错误：

All 6 json files are grabbed from the absolute URL path by Node JS. I have made 2 more yesterday and everything was working fine. However, today I made one and implemented the same way and received the following error:

没有'Access-Control-Allow-Origin'标头存在于请求的资源上。因此，不允许访问原始空。

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.

我正在以相同的方式实现，例如：

I am implementing each the same way, example:

var base_url = 'http://127.0.0.1:8080';

mainInformationTop();

function mainInformationTop()
{
    $.ajax({
        type: "GET", 
        url: base_url + "/api/topInformation.json", 
        dataType: "json",
        success: function(response)
        {
            var json_obj = response.mainDescription;
            var imagesSlider="";
            var imagesSliderDescription ="";
            for (var i = 0; i< json_obj.length; i++) 
            {

            }

        }
        , 
        error: function(jqXHR, textStatus, errorThrown) {
            alert(jqXHR.status);
        }  
    })    
}

我认为json文件不相关，但下面是我的json文件：

I don't think the json file is relevant but below is my json file:

{"mainDescription":[
{
"display": "my display",
"description" : "my description"
}
]}

我已取出信息在for循环中进行测试以及我的附加内容，因为无关紧要。由于某种原因，它会失败，并会出错而不是成功。所有其他调用都以相同的方式设置并正常工作。

I have took out the information in the for loop for testing as well as my append because irrelevant. For some reason it fails and goes to error instead of success. All other calls are set up the same way and work correctly.

推荐答案

这是获得相同效果的答案：

var fs = require('fs');
var express = require('express');
var cors = require('cors');

var app = express();

app.use(cors()); 
app.use(express.static(path.join(__dirname, '../')));

app.get('/', function (req, res) { 
  res.writeHead(200, {'Content-Type': 'text/plain'});
  contents = fs.readFileSync('sliderImages.json', 'utf8');
  res.end(contents);
});

app.listen(process.env.PORT || 8080);

这篇关于Node.Js错误“在请求的服务器上没有'Access-Control-Allow-Origin'标头”。的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！