Question

I am returning a JSON array to my jQuery function script, but cannot seem to get the syntax correct — even after reading about a dozen different examples here.

Here is the calling jQuery ajax function:

$.ajax({
    url: "fetchAlleles.php",
    datatype: 'json',
    data: {'mndx': mndx, 'sndx': sndx },
    success: function(rtnval) {
      alert("success: allele_1="+rtnval['allele_1']+", allele_2="+rtnval['allele_2']);
      //alert(rtnval);
    },
    error: function() { alert('Error!'); }
    });

Here is the PHP code that returns the values:

echo "{";
echo "allele_1: ", json_encode($ary[0]), "\n";
echo "allele_2: ", json_encode($ary[1]), "\n";
echo "run_date: ", json_encode($ary[2]), "\n";
echo "}";

If I use my alert debugging statement, I can see what’s being returned is what I expect:

{allele_1: "440"
allele_2: "480"
run_date: null
}

but anything else I try to read the values inside the JSON object comes back “undefined”, whether it’s

alert("success: allele_1="+rtnval['allele_1']+", allele_2="+rtnval['allele_2']);

or

alert("success: allele_1="+rtnval.allele_1+", allele_2="+rtnval.allele_2);

or

alert("success: allele_1="+rtnval['allele_1'][0]+", allele_2="+rtnval['allele_2'][0]);

Hope someone can help — this is exasperating! (Wish JSON syntax were more obvious!)

thanks much,
rixter

Answer 1

Use jQuery.parseJSON to make this easier http://api.jquery.com/jQuery.parseJSON/

Here’s their example:

var obj = jQuery.parseJSON('{"name":"John"}');
alert( obj.name ); //John