Javascript highchart passing a variable

Question

I used the $.get to get the value generated in test2.php, when I do an alert(data) I get the exact value I want, but I don't know what to do to stock the value obtained in the variable y :

   var series = this.series[0];  
   setInterval(function() {

      $.get('test2.php', function(data) {
         alert(data);
      });

      var y = data;  // NOT WORKING !
      var x = (new Date()).getTime();     

      series.addPoint([x, y], true, true);
    }, 1000);

I'm new to JavaScript, so thanks in advance..!

Kevin Bowersox · Accepted Answer · 2013-06-11 09:21:29Z

2

Javascript uses function scope and Ajax is asynchronous, data is not in scope in the code you execute after the Ajax call. Placing the var y = data; and subsequent code outside the callback causes it to execute before the response from the server is received.

Adding this code inside the callback will cause it to execute once a response from the server is received and when data actually contains the response.

   var series = this.series[0];  
   setInterval(function() {

      $.get('test2.php', function(data) {
         alert(data);
         var y = parseInt(data);  // NOT WORKING !
         var x = (new Date()).getTime();     

         series.addPoint([x, y], true, true);
      });

    }, 1000);

edited Jun 11, 2013 at 9:21

answered Jun 11, 2013 at 8:48

Kevin Bowersox

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1 Comment

Kevin Bowersox Over a year ago

@Falcon, checkout parseInt or parseFloat to convert String to Number

Jan Turoň · Accepted Answer · 2013-06-11 11:47:37Z

$.get is probably jQuery AJAX call, where A stands for Asynchronous. The order of the events is

$.get is called, waiting for response and call the second parameter function after the response comes
var y = data;, but the response setting the data haven't been sent yet (the rest of the function (setPoint is processed, too)
the response comes from server and sets data (too late)

There are two workarounds:

either put the code into the $.get function in the second parameter (as Kevin Bowersocks suggests)

or do a synchronous call. jQuery won't help you here and I can't recommend it: the browser freezes until the response and if the response is lost, page needs to be reloaded.

var xhr = new XMLHttpRequest();
xhr.open("GET","test2.php",false); // false = synchronous call
xhr.send(); // browser freezes until the response, let's hope not for long
var y = xhr.response; // response is ready here for synchronous calls

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