Difference between revisions of "Display stock quotes from Yahoo!"

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<html><div id="debug"></div></html>
 
<html><div id="debug"></div></html>
 
===The underlying JavaScript code===
 
===The underlying JavaScript code===
<source lang="xml">
+
<source lang="javascript">
<jsxgraph width="700" height="400">
 
 
var hi, lo, brd, periodical,  
 
var hi, lo, brd, periodical,  
 
     brd, g, txt, val,
 
     brd, g, txt, val,
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   }
 
   }
 
};
 
};
 
</jsxgraph>
 
  
 
</source>
 
</source>

Revision as of 15:33, 7 June 2011

This JSXGraph application fetches the live stock quotes of the German DAX Index (gdaxi) from Yahoo!. The curve is updated only once a second, so initially it needs a little patience until the curve is visible.

Beware that in order to simplify the handling of AJAX we use the additional library prototype.js in this example.

The underlying JavaScript code

var hi, lo, brd, periodical, 
    brd, g, txt, val,
    x = [],
    y = [];


fetchData = function() {
    new Ajax.Request('/ajax/stockquotes.php', {
        onComplete: function(transport) {
            var t, a;
            if (200 == transport.status) {
                t = transport.responseText;
                a = t.split(',');
                x.push(x.length+1);
                y.push(a[1]);
                val = a[1];  // set the text
                if (!g) { 
                    g = brd.createElement('curve', [x,y],{strokeWidth:3, strokeColor:'green',shadow:true}); 
                    txt = brd.createElement('text', [3,(hi+lo)*0.5,function(){return 'GDAXI = '+val;}],{fontSize:'14px'}); 
                    brd.createElement('functiongraph',[JXG.Math.Numerics.regressionPolynomial(1,g.dataX,g.dataY)],{strokecolor:'red',dash:3});
                } else {
                    g.dataX = x;                    
                    g.dataY = y;
                }
                brd.update();
            };
    }});
};

// Fetch max and min, and start the periodical update.
new Ajax.Request('/ajax/stockquotes.php', {
        onComplete: function(transport) {
            var a, t;
            if (200 == transport.status) {
                t = transport.responseText;
                a = t.split(',');
                hi = a[6]*1.00002;
                lo = a[7]*0.99998;
                brd = JXG.JSXGraph.initBoard('jxgbox', {axis:true, boundingbox:[0,hi,200,lo]});
                brd.createElement('axis',[[0,lo],[1,lo]]);
                Start();
            };
    }});


Start = function() {
   if (periodical==null) {
      periodical = setInterval(fetchData,1000);  // Start the periodical update
   }
};

Stop = function() {
   if (periodical!=null) {
       clearInterval(periodical);
       periodical = null;
   }
};

The PHP code

<?php
$fp = fopen ("http://finance.yahoo.com/d/quotes.csv?s=^gdaxi&f=sl1d1t1c1ohgv&e=.csv","r");
echo fgets ($fp, 1024);
fclose ($fp);
?>