Javascript array reference

Question

If I have the following:

{"hdrs": ["Make","Model","Year"],
 "data" : [ 
   {"Make":"Honda","Model":"Accord","Year":"2008"}
   {"Make":"Toyota","Model":"Corolla","Year":"2008"}
   {"Make":"Honda","Model":"Pilot","Year":"2008"}]
}

And I have a "hdrs" name (i.e. "Make"), how can I reference the data array instances? seems like data["Make"][0] should work...but unable to get the right reference

EDIT

Sorry for the ambiguity.. I can loop through hdrs to get each hdr name, but I need to use each instance value of hdrs to find all the data elements in data (not sure that is any better of an explanation). and I will have it in a variable t since it is JSON (appreciate the re-tagging) I would like to be able to reference with something like this: t.data[hdrs[i]][j]

You're missing a comma between the array values in the data array. — Jared
– Jared, Commented Sep 17, 2008 at 19:50
thanks a lot for the help..yes, I changed the names for the post and messed up the syntax, thanks again — Jay Corbett
– Jay Corbett, Commented Sep 17, 2008 at 20:40

Jared · Accepted Answer · 2008-09-17 19:58:24Z

4

I had to alter your code a little:

var x = {"hdrs": ["Make","Model","Year"],
         "data" : [ 
           {"Make":"Honda","Model":"Accord","Year":"2008"},
           {"Make":"Toyota","Model":"Corolla","Year":"2008"},
           {"Make":"Honda","Model":"Pilot","Year":"2008"}]
        };

        alert( x.data[0].Make );

EDIT: in response to your edit

var x = {"hdrs": ["Make","Model","Year"],
         "data" : [ 
           {"Make":"Honda","Model":"Accord","Year":"2008"},
           {"Make":"Toyota","Model":"Corolla","Year":"2008"},
           {"Make":"Honda","Model":"Pilot","Year":"2008"}]
        };
var Header = 0; // Make
for( var i = 0; i <= x.data.length - 1; i++ )
{
    alert( x.data[i][x.hdrs[Header]] );
}

edited Sep 17, 2008 at 19:58

answered Sep 17, 2008 at 19:49

Jared

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Comments

just mike · Accepted Answer · 2019-12-14 15:41:58Z

2

First, you forgot your trailing commas in your data array items.

Try the following:

var obj_hash = {
    "hdrs": ["Make", "Model", "Year"],
    "data": [
        {"Make": "Honda", "Model": "Accord", "Year": "2008"},
        {"Make": "Toyota", "Model": "Corolla", "Year": "2008"},
        {"Make": "Honda", "Model": "Pilot", "Year": "2008"},
    ]
};

var ref_data = obj_hash.data;

alert(ref_data[0].Make);

@Kent Fredric: note that the last comma is not strictly needed, but allows you to more easily move lines around (i.e., if you move or add after the last line, and it didn't have a comma, you'd have to specifically remember to add one). I think it's best to always have trailing commas.

edited Dec 14, 2019 at 15:41

answered Sep 17, 2008 at 19:50

just mike

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1 Comment

Kent Fredric Over a year ago

[{},{},{},] <-- last comma here not needed.

Domenic · Accepted Answer · 2008-09-17 19:48:38Z

1

So, like this?

var theMap = /* the stuff you posted */;
var someHdr = "Make";
var whichIndex = 0;
var correspondingData = theMap["data"][whichIndex][someHdr];

That should work, if I'm understanding you correctly...

answered Sep 17, 2008 at 19:48

Domenic

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Comments

Kent Fredric · Accepted Answer · 2008-09-17 19:50:04Z

1

var x = {"hdrs": ["Make","Model","Year"],
 "data" : [ 
   {"Make":"Honda","Model":"Accord","Year":"2008"}
   {"Make":"Toyota","Model":"Corolla","Year":"2008"}
   {"Make":"Honda","Model":"Pilot","Year":"2008"}]
};

x.data[0].Make == "Honda"
x['data'][0]['Make']  == "Honda"

You have your array/hash lookup backwards :)

answered Sep 17, 2008 at 19:50

Kent Fredric

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Comments

noah · Accepted Answer · 2008-09-17 19:50:55Z

1

I'm not sure I understand your question, but...

Assuming the above JSON is the var obj, you want:

obj.data[0]["Make"] // == "Honda"

If you just want to refer to the field referenced by the first header, it would be something like:

obj.data[0][obj.hdrs[0]] // == "Honda"

answered Sep 17, 2008 at 19:50

noah

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Comments

Adam Weber · Accepted Answer · 2008-09-17 19:47:50Z

0

perhaps try data[0].Make

answered Sep 17, 2008 at 19:47

Adam Weber

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Comments

Stephen Wrighton · Accepted Answer · 2008-09-17 19:48:18Z

0

Close, you'd use

var x = data[0].Make;
var z = data[0].Model;
var y = data[0].Year;

answered Sep 17, 2008 at 19:48

Stephen Wrighton

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Comments

DGM · Accepted Answer · 2008-09-17 19:50:36Z

0

Your code as displayed is not syntactically correct; it needs some commas. I got this to work:

$foo = {"hdrs": ["Make","Model","Year"],
 "data" : [ 
   {"Make":"Honda","Model":"Accord","Year":"2008"},
   {"Make":"Toyota","Model":"Corolla","Year":"2008"},
   {"Make":"Honda","Model":"Pilot","Year":"2008"}]
};

and then I can access data as:

$foo["data"][0]["make"]

answered Sep 17, 2008 at 19:50

DGM

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1 Comment

Jay Corbett Over a year ago

thanks for the response, you are right about the commas, I changed the names for the post and messed up the syntax

Jay Corbett · Accepted Answer · 2008-09-17 20:36:48Z

0

With the help of the answers (and after getting the inside and outside loops correct) I got this to work:

var t = eval( "(" + request + ")" ) ;
for (var i = 0; i < t.data.length; i++) {
 myTable +=    "<tr>";
 for (var j = 0; j < t.hdrs.length; j++) {
  myTable += "<td>" ;
   if (t.data[i][t.hdrs[j]] == "") {myTable += "&nbsp;" ; }
    else { myTable += t.data[i][t.hdrs[j]] ; }
  myTable += "</td>";
 }
 myTable +=    "</tr>";
}

answered Sep 17, 2008 at 20:36

Jay Corbett

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