How to select javascript array key using variable?

Question

I have this json:

var myjson = [
    {"ID":1, "FullName":"Breese Dantour"},
    {"ID":2, "FullName":"Danny Xirjav"},
    {"ID":3, "FullName":"Ben Falco"}
]

And I tried to catch it by it's key using an array:

var mykey = new array();
mykey.push("ID");
mykey.push("FullName");

var res = "";
for (var i = 0; i < myjson.length; i++) {
   var inner;
   for (var c=0; c < mykey.length; c++){
      inner = inner + "<td>" + myjson[i].mykey[c] + "</td>";
   }
   res = res + "<tr>" + inner + "</tr>\n";
}
alert(res);

And i got this error :

Error: TypeError: myjson[i].mykey is undefined

I know this happen because mykey is not the key of myjson. But I want that mykey returning it's value so it read as myjson key.
Any other ways?

Also var mykey = new array(); should be var mykey = new Array(); — roxxypoxxy
– roxxypoxxy, Commented May 7, 2014 at 8:46

Sebastien C. · Accepted Answer · 2014-05-07 08:42:05Z

2

Try this :

var mykey = new array();
mykey.push("ID");
mykey.push("FullName");

var res = "";
for(var i = 0; i < myjson.length; i++){
   var inner = "";
   for (var c=0; c < mykey.length; c++){
      inner = inner+"<td>"+myjson[i][mykey[c]]+"</td>";
   }
   res = res+"<tr>"+inner+"</tr>\n";
}
alert(res);

answered May 7, 2014 at 8:42

Sebastien C.

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Comments

Alexander Suraphel · Accepted Answer · 2014-05-07 08:42:51Z

1

Replace myjson[i].mykey[c] by myjson[i][mykey[c]]

The reason this works is that the dot operator(.) has higher precedence than [] so the former expression is evaluated as (myjson[i].mykey)[c] which gives you undefined because myjson[i] doesn't have the property mykey.

answered May 7, 2014 at 8:42

Alexander Suraphel

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Comments

Artem Petrosian · Accepted Answer · 2014-05-07 08:41:35Z

1

You can get array elements by key like this:

myjson[i][ mykey[c] ];

answered May 7, 2014 at 8:41

Artem Petrosian

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