Question

I get from server into client side only pure number IDs, how to add dynamically it to html hidden field so that looks like array or JSON format (I mean: ["32","33","34"]), so that in next step I can receive on serwer and parse? Hidden field contains on start only blank brackets [].

My current code override hidden field from [] to e.g. "32":

$("#myHiddenField").val(JSON.stringify(data.result[0].newid));

Answer 1

You can use $.parseJSON() to deserialize the array from the hidden input value, push() the new item, then serialize the array again:

var $hiddenField = $("#myHiddenField");
var results = $.parseJSON($hiddenField.val());
results.push(data.result[0].newid);
$hiddenField.val(JSON.stringify(results));

However, it might be more efficient to keep track of the array as items are added, and only serialize it when the form is submitted (in a submit event handler, for instance).