如何在Javascript中访问JSON数组

Question

How do i get "LSZ09".

var el1=data[0];
alert(el1);

This gives me "a" from array, as position 1 gives me r, 2 r, 3 a, 4y ,..

The array is received through a " echo json_encode($punten); "

Also when i try

var jsonDataArray = JSON.parse(data);

I get a syntax error:

SyntaxError: JSON.parse: unexpected character

Code:

$.ajax({ url: 'getPunten.php',
                        data: {statnam: jSelectedStation[0]},
                        type: 'get',
                        success: function(data) {

Received from php script, with last line being: echo json_encode($punten);

[{"STATDEV":"LSZ09 ","0":"LSZ09 ","DEVPKT":"1","1":"1","PKTTYP":"S","2":"S","KARTNR":"0","3":"0","BITNRK":"1","4":"1","BITSTATUS":"0","5":"0","TYPE":"I ","6":"I "},{"STATDEV":"LSZ10 ","0":"LSZ10 ","DEVPKT":"1","1":"1","PKTTYP":"S","2":"S","KARTNR":"0","3":"0","BITNRK":"2","4":"2","BITSTATUS":"0","5":"0","TYPE":"I ","6":"I "}

php:

$db = new PDO ("xxxx");
$qry="SELECT r.refnam, r.zustnr FROM refdev r INNER JOIN (SELECT refnam, COUNT(*) cnt FROM refdev rc GROUP BY refnam) rc ON rc.refnam = r.refnam LEFT OUTER JOIN texte t ON r.sigtnr = t.textnr WHERE rc.cnt = $aantal AND t.tstring LIKE '%$tekst%' ORDER BY r.refnam, r.zustnr";
$filterQry = $db->query($qry);
$filtered = $filterQry->fetchAll();
echo json_encode($filtered);

Answer 1

If that php you've shown is the one you're using,no, it won't work.

You see, the text that gets passed to the javascript includes the results of both var_dump and echo .

Consider the following php code:

<?php
    $filtered = array(1,2,3);
    var_dump($filtered);
    echo json_encode($filtered);    
?>

What do you think the result of this is? Hint: it's not what you've been expecting. You seem to be expecting it to be

 [1,2,3]

Well, it is - at least in part. That's the output of the last line only. But we've not considered the middle line var_dump($filtered); - the code that will output something similar to the code you've labelled with Received from php script, with last line being: echo json_encode($punten);

The output of my snippet is actually:

array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) } [1,2,3]

That's why you're getting the first 5 elements containing 'a' 'r' 'r' 'a' 'y'!! Its also why the call to JSON.parse(data); fails - "arrray(3)" isn't valid json.

Hint: when you navigate to the php script with a browser, what you see there is what will be retrieved with an ajax call.