Javascript: How to output array in array with for loop

Question

I´m trying to output the array fields of an array with ist in an Array (More dimensional array). It seems .length does not work in the second array.

Thanks for help!

cheers, toni

<html><head><title>Test</title>
</head><body>
<script type="text/javascript">
var Mitarbeiter = new Array();

Mitarbeiter[0] = new Object();
Mitarbeiter[0]["Name"] = "Hotels";
Mitarbeiter[0]["data"] = new Object();
Mitarbeiter[0]["data"][0] = "Ort 1";
Mitarbeiter[0]["data"][1] = "Ort 2";

Mitarbeiter[1] = new Object();
Mitarbeiter[1]["Name"] = "Restaurants";
Mitarbeiter[1]["data"] = new Object();
Mitarbeiter[1]["data"][0] = "Ort 2";
Mitarbeiter[1]["data"][1] = "Ort 4";



for (var i = 0; i < Mitarbeiter.length; i++) {

document.write("<b>" + i + " : " + Mitarbeiter[i]["Name"] + "</b><br />");

//works
alert (Mitarbeiter[0]["data"][i]);


// works not
for (var f = 0; f < Mitarbeiter[i]["data"].length; f++){
document.write("<br/>&nbsp;" + Mitarbeiter[i]["data"][f]);
}
}
</script>
</body>
</html>

It's because you call ["data"] = new Object(); . You need ["data"] = new Array(); or just: ["data"] = []; Otherwise it's an object. — user1150525
– user1150525, Commented Apr 30, 2012 at 14:11
Mitarbeiter[0]["data"] = new Object(); -- You mean new Array()? — Brad Christie
– Brad Christie, Commented Apr 30, 2012 at 14:11
@Alnitak: Same difference. new Array() is synonymous with []. — Brad Christie
– Brad Christie, Commented Apr 30, 2012 at 14:25
@BradChristie and nowadays considered the incorrect way of doing it. Will post reference when I find it. — Alnitak
– Alnitak, Commented Apr 30, 2012 at 14:26

aquinas · Accepted Answer · 2012-04-30 14:13:02Z

2

Mitarbeiter[0]["data"] = new Object();

Should be

Mitarbeiter[0]["data"] = new Array();

answered Apr 30, 2012 at 14:13

aquinas

23.9k5 gold badges60 silver badges82 bronze badges

No @Alnitak it should be: mitarbeiter[0]["data"] = []; because mitarbeiter shouldn't be using a capital letter. :)

aquinas
– aquinas

04/30/2012 14:51:48
Commented Apr 30, 2012 at 14:51

Add a comment |

Alnitak · Accepted Answer · 2012-04-30 14:20:48Z

0

You can create the whole thing in one go using an "object literal":

var Mitarbeiter = [ {
    Name: 'Hotels',
    data: [ 'Ort 1', 'Ort 2' ]
  }, {
    Name: 'Restaurants',
    data: [ 'Ord 2', 'Ort 4' ]
  }
];

Note how the braces indicate the type of object - [ ... ] for a linear array, { ... } for a "normal" Javascript object.

Your data: fields use numeric indices and so should be arrays rather than objects, so use [ ... ] syntax.

answered Apr 30, 2012 at 14:20

Alnitak

341k72 gold badges418 silver badges502 bronze badges

Add a comment |

Guss · Accepted Answer · 2012-04-30 14:16:34Z

Your "data" fields are Objects (i.e. property lists or dictionaries) and not arrays, and as such have not length property. The construct

var data = new Object();
data[0] = "Ort 1";
data[1] = "Ort 2";

is identical to

var data = { 0: "Ort 1", 1: "Ort 2" };

Where obviously there is no length to be found.

I would have written the whole thing like this:

var Mitarbeiter = new Array();

Mitarbeiter.push( { 
    Name: "Hotels",
    data: [ "Ort 1", "Ort 2" ]
});

Mitarbeiter.push( {
    Name: "Restaurants",
    data: [ "Ort 2", "Ort 4"] 
});

I think its more concise and easier to understand.

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