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I am trying to send JSON data to the server and receive. here is my server API code:

   var express    = require('express');      
   var app        = express();               
   var bodyParser = require('body-parser');

   app.use(bodyParser.urlencoded({ extended: true }));
   app.use(bodyParser.json());

   var port = process.env.PORT || 8080;        
   var router = express.Router();             
   app.use('/api', router); 

   router.post('/', function (req, res) 
   {
     res.json({ message: 'you are doing post ' });   
   })

  app.listen(port);
  console.log('Magic happens on port ' + port);

I have tested it with "postman" and it responded fine.

when I trying to get response from a client with the following code

function BestTourModel() 
{
    var self = this;
    self.serverURI = 'http://localhost:8080/api';

    self.ajax = function(uri, method, data) 
    {
        var request = {
                        url: uri,
                        type: method,
                        contentType: "application/json",
                        accepts: "application/json",
                        cache: false,
                        dataType: 'json',
                        data: JSON.stringify(data),
                        success: function(data){alert(data);},
                        failure: function(errMsg) { alert(errMsg);}
                       };
        return $.ajax(request);
    }

    self.run_algorithm = function()
    {
        if(self.input_value())
        {               
            var markers = [{ "a": "11", "b": "7" },
                           { "a": "44", "b": "19" },
                           { "a": "45", "b": "-3" }];

            self.ajax(self.serverURI(), 'POST', markers).done(function(data) 
            {
                console.log(data); //this prints received data
            });
        }

    }
}

var bestTourModel = new BestTourModel();
ko.applyBindings(bestTourModel, $('#main')[0]);

the "run_algorithm " is bound to an html button.

<button class="btn" data-bind="click: $root.run_algorithm" >Run</button>

I was tring to confirm the connection by sending the shown JSon data and hoping to receive something, so I can send my real data. but I got error in chrom debugger, shown below.

XMLHttpRequest cannot load http://localhost:8080/api. Response to preflight 
request doesn't pass access control check: No 'Access-Control-Allow-Origin'
header is present on the requested resource. Origin 'null' is therefore not
allowed access.

Please point out what I am doing wrong. I am new to this, please explain in a simple way.

Thanks!

arslan
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1 Answers1

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After googling and reading many posts, find the solution here The original idea was given here

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arslan
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