Create JSON in Javascript

Question

I would like to create a dynamic JSON array in Javascript like that :

var jsonData = {
 "Tasks" : [
 {
 "__metadata" : {
 "uri" : "...",
 "type" : "..."
 },
 "ID" : "...",
 "Category" : "..",
 // ...
 },
 {
 "__metadata" : {
 "uri" : "...",
 "type" : "..."
 },
 "ID" : "...",
 "Category" : "..",
 // ...
 },
 // others tasks
 ], "__count" : "2"
};

I found how to create a JSON in Javascript but not with this syntax. So what is the good way to create the JSON object with the 'Tasks' array and add items in it ?

Thank you for your help

• Qantas 94 Heavy: What do you mean by "dynamic"?
• Oskar: Does this help: stackoverflow.com/questions/4314008/…
• kennypu: your question doesn't make sense. you already have the javascript you want, all you need to call is JSON.stringify() on it and you're done.
• Amberlamps: Also the __count attribute is redundant. It is already stored within the Tasks array.
• Felix Kling: This is an object literal, not JSON. Please use the correct terminology, otherwise it is difficult to understand your problem. But I believe the answer is: you can't. You can create the initial object with an object literal and then add the data to the array later.

Answer 1

Something like this maybe?

function Metadata(uri,type)
{
 this.uri = uri;
 this.type = type;
}
function Task(metadata, id, category)
{
 this.__metadata = metadata;
 this.ID = id;
 this.Category = category;
}
var tasks = [new Task(new Metadata('foo','bar'), 1, 'blah'), new Task(new Metadata('foo1', 'bar1'), 2, 'blah2')];
document.write(JSON.stringify({"Tasks": tasks, "__count": tasks.length}));

Answer 2

Create objects with constructors and use the JSON api.

var jsonData = {};
jsonData.Tasks = new Array();
var Metadata = function(uri, type){
 this.uri = uri;
 this.type = type;
}
var Task = function (metadata, id, category){
 this.__metadata = metadata;
 this.ID = id;
 this.Category = category;
}
var tasks = jsonData.Tasks;
tasks.push(
 new Task(
 new Metadata("someUri", "someType"),
 1,
 "someCategory")
);

jsbin: working example

Answer 3

I'm using this code and it works :

var jsonData = {};
jsonData.Tasks = [];
var count = 0;
for(...) {
 jsonData.Tasks.push({
 "__metadata" : {
 "uri" : "...",
 "type" : "..."
 },
 "ID" : "...",
 "Category" : "...",
 });
 count++;
}
jsonData.__count = count;

Thank you for your answers and your reactivity !

• Yoeri: I still recommend you use objects rather than string literals. I don't know what it means performance whise, but is a lot less error prone.