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how to create array of json object without key in javascript

I want to create an array of JSON object without a key.How can this is achieved ..??
for example [{8,0,2}, {20,0,2}].
var hh = 9
var mm = 8
var qty = 2
var data = [];
data.push({hh,mm,qty})
it gives data like [{hh:9,mm:8,qty:2}]
I want array like [{9,8,2},{9,3,4}]

You example uses a new feature of ECMAScript 6 that is the shorthand syntax for initialising object properties. This line in your example:
data.push({hh,mm,qty});
is equivalent to this verbose one:
data.push({hh: hh, mm: mm, qty: qty});
An object in JavaScript will always have keys and values. There is no way to save just values in a plain object. However, there are two other solutions.
One is using an array:
data.push([hh, mm, qty]);
Note the square brackets substituting the curly ones. This will obviously push an array of three values onto the data array. When retrieving the values, you can just refer to their index, as an array's items will always retain their indices:
var data2 = [hh, mm, qty];
var hh2 = data2[0];
var mm2 = data2[1];
var qty2 = data2[2];
Another way of just "saving the values" is using a set, though the construction of a Set object will still require passing it an array:
data.push(new Set([hh, mm, qty]));
Accessing the data is less straightforward in this case, as the set will typically only let you iterate it. Unlike similar data structures in other languages, a JavaScript set will retain the order of inserted values. It can therefore be safely converted into an array:
var mySet = new Set([hh, mm, qty]);
var data3 = Array.from(mySet);
var hh3 = data3[0];
var mm3 = data3[1];
var qty3 = data3[2];
You can read more about sets here.

You can wrap it over another JSON object with a key I assume you want a JSON object.
Like this { [{8,0,2}, {20,0,2}] } but this with a problem - It is not a valid JSON.
I had a similar problem for one of my scenario. Then I realised
A top level JSON can't exist without a key!
Consider this example, you have another KV pair in JSON and also this array.
{
"somekey" : "somevalue",
[ {8,0,2}, {20,0,2} ]
}
You can fetch "somevalue" with the key "somekey". But how would you access the array? you can't :(
I would suggest you to use a top level key for the JSON and make this array as value of it's. Example:
{
"my array" : [ {8,0,2}, {20,0,2} ]
}

Without a key value pair, the object was not created. That's why its adding a key using the variable name
Look at this error. Its invalid code
var a = [{8,0,2}, {20,0,2}];
console.log(a)
You could push to an array instead of an object
var data = [];
var hh = 9
var mm = 8
var qty = 2
var data = [];
data.push([hh,mm,qty])
console.log(data)

You can't.
Object Literal Property Value Shorthands allow you to create an object where the property names are inferred from the variable names you use to pass the data into.
If you don't have variable names, then there is nothing for the JS engine to use to figure out what the property names should be.
Consider using a function instead.
console.log([time(8,0,2), time(20,0,2)]);
function time (hh, mm, qty) {
return {hh, mm, qty};
}

The result you get at the end makes sense. By doing {hh,mm,qty} you are effectively saying "Use the variable name as the key and its value as the value". It might help us more if you provide an example of how you intend to use the result and access the variables i.e. the shape of the object you want in the end.
That being said, there are a couple alternatives:
Using values as the keys
If you really wanted your object to look similar to {8,0,2} you could use those values as the keys (all keys get converted to strings anyways) so you could do the following:
var example1 = {8:undefined,0:undefined,2:undefined};
var example2 = {8:null,0:null,2:null};
var keys = [];
for(var name in example1) {
keys.push(name);
}
// keys = ["8","0","2"];
var otherKeys = Object.keys(example2);
// otherKeys = ["8","0","2"];
Setting the keys dynamically
var hh = 9;
var mm = 8;
var qty = 2;
var obj = {};
obj[hh] = null;
obj[mm] = null;
obj[qty] = null;
//obj = {9:null,8:null,2:null};
I'm not certain if this solves your problem or answers your question entirely but it might give you some more insight into what is happening and why. The above examples are a common way to create a quick lookup versus a dictionary with would have values in place of null or undefined.

How to make associative array with number as string in Javascript

I have a code :
var index = 100;
var arr =[];
arr[index.toString()] = "Hello"
The result : index still known as integer not a string. Anyone can explain what's wrong with my code?

You have to declare associative arrays using {}, which creates a new object, because in JavaScript, arrays always use numbered indexes.
You need to declare an object: var arr={};
arrays use numbered indexes.
objects use named indexes.
var index = 100;
var arr ={};
arr[index.toString()] = "Hello";
console.log(arr);

How to make associative array with number as string in Javascript
JavaScript doesn't have associative arrays in the sense that term is frequently used. It has objects, and as of ES2015 (aka "ES6"), it has Maps.
The result : index still known as integer not a string. Anyone can explain what's wrong with my code?
The index variable's value is still a number, yes, because you haven't done anything to change it. But the index in the array is a string (and would be even if you didn't use .toString()), because standard arrays aren't really arrays at all1, they're objects with special handling of a class of properties (ones whose names are strings that fit the spec's definition of an array index), a special length property, and that use Array.prototype as their prototype.
Here's proof that array indexes are strings:
var a = [];
a[0] = "zero";
for (var name in a) {
console.log("name == " + name + ", typeof name == " + typeof name);
}
That said, you don't want to use an array when you want a generic object or map.
Here's using a generic object for name/value mappings:
var o = Object.create(null);
var name = "answer";
o[name] = 42;
console.log(o[name]); // 42
The property names in objects are strings or (as of ES2015) Symbols. I used Object.create(null) to create the object so it wouldn't have Object.prototype as its prototype, since that gives us properties (toString, valueOf, etc.) that we don't want if we're using the object as a map.
Here's using a Map:
var m = new Map();
var name = "answer";
m.set(name, 42);
console.log(m.get(name)); // 42
The main advantages Maps have over objects are:
Their keys can be anything, not just strings or Symbols
They're iterable, so you can use for-of to loop through the mappings they contain
Maps have a size property telling you how many entries they have
Maps guarantee that iteration of their entries is performed in the order the entries were added to the map

With ES6, you could use a Map, which holds any type as key.
var map = new Map;
map.set(100, "Hello");
map.set('100', "Foo");
console.log(map.get(100)); // 'Hello'
console.log(map.get('100')); // 'Foo'
console.log([...map]);

JavaScript does not support arrays with named indexes, in JavaScript, arrays always use numbered indexes.
If you use a named index, JavaScript will redefine the array to a standard object.
After that, all array methods and properties will produce incorrect results.
As you can see in the following example:
var person = [];
person["firstName"] = "John";
person["lastName"] = "Doe";
person["age"] = 46;
var x = person.length; // person.length will return 0
console.log(x);
var y = person[0]; // person[0] will return undefined
console.log(y);

Can Javascript objects be accessed like arrays?

Assuming an object is initialized as following:
var myObj = {
"key1":"val1",
"key2":"val2",
"key3":"val3",
...
};
Can I retrieve key values like this?
var retrKey1 = myObj[0];
var retrKey2 = myObj[1];
var retrKey3 = myObj[2];
...
The issue I am trying to solve is that I need to pick random key values from this object. Generating a random number is not an issue, but:
How can I retrieve the number of keys in the object/map?
Can I retrieve the key values using a integer index like in arrays?
If not, what are my options?

The Object.keys method returns an array of object properties. You can index the array with numbers then.
var myObj = {
"key1":"val1",
"key2":"val2",
"key3":"val3",
...
};
var keys = Object.keys(myObj);
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

No, because there's no ordering among property keys. If you want ordered keys, you need to work with an array.
You could define a structure like this :
var myObj = [
{key:"key1", val:"val1"},
...
];

insert an array with a custom name into a two dimensional array - javascript

I have a two dimensional array which I created like this
var books = new Array(); // create an Array
var book1 = new Array();
book1.push("1");
book1.push("adfgsdg");
book1.push("dfgsdfg");
book1.push("dfgds");
book1.push("44.95");
book1.push("dfgsd");
book1.push("dfgsdg");
books.push(book1);
var book2 = new Array();
book2.push("2");
book2.push("gdhff");
book2.push("fghfd");
book2.push("fghdf");
book2.push("44.95");
book2.push("2000-12-16");
book2.push("fghfghd");
books.push(book2);
can you tell me how to dynamically create a new book3, book4.... array and push into the books array.

Just use an object:
var books = {book1: ['book1 title', 'book1 - title2']};
books['book2'] = ['book2 titles'];
books.book3 = [];//works, too
books.book3.push('foobar');
If you insist on having variables that reference a particular array, that's very easily done:
var book2 = books.book2;//arrays are objects, so:
book2.push('A second title');
console.log(books.book2[1]);//logs "A second title"
Easy-peasy. on the dynamic names front, just a quick example:
books['book' + someVar] = [];
Works just fine.
As #raghaw pointed out, perhaps you could do with some explaining:
JavaScript doesn't really support associative arrays as such, instead objects are used (even Array's are just "pimped" objects, but that's a different matter)
You can create a new instance of any object by calling the construct (new X(), like you did), but in case of native object types (like Array and Object), that's not to be recommended (new Array(10); and new Array('10') behave differently, for example).
In those cases the literal notation is to be preferred:
var wrong = new Object();//not "wrong", but impredictable
var better = {};//or new [whateverTypeOfObject]();
//ditto for arrays:
var dangerous = new Array();
var safe = [];
To assign an object/array with a certain set of values already there, simply fill them in:
var myObject = {key: "value",
theValue: {can: 'be',
anything: ["even", "another", "object"]}
};
The data can be accessed both by using the dot-notation or the bracket notation:
console.log(myObject.theValue['can']);//be
//===
console.log(myObject.theValue.can);//be
//===
console.log(myObject["theValue"]["can"]);//be
If you're using variables as keys, you'll have to use the bracket notation. If you feel like you need more info check out MDN, spend some time on that site - it's a good reference on JS

First of all I think that the answer by Elias is very good. However, if you are not in the mood of going OO, just create books 3 and 4 as raghavv told in the comment, then push them all in the books array
books.push(books1);
books.push(books2);
books.push(books3);
books.push(books4);
The result of it will be actually something like
var books[
books1[value1, value2, value3],
books2[value1, value2, value3],
books3[value1, value2, value3],
books4[value1, value2, value3]
];

add anonymous object to an object

I know to add a named object to an existing JavaScript object you do this:
var json = {};
json.a = {name:"a"};
But how can you add an object to an existing JavaScript object in a similar fashion without assigning it an associative name, so that it could be accessed by a for() statement. Sorry if I'm being a little vague, I don't know a lot about JavaScript objects.
UPDATE:
I want the end result to look like this:
var json = [{name:'a'}{name:'b'}];

What you have there is not strictly a JSON object. You're using JS object literals rather.
You can do this:
var jsObj = {};
// add a 'name' property
jsObj = { name: 'a'};
var anotherObj = { other: "b" };
// will add 'other' proprty to jsObj
$.extend(jsObj, anotherObj);
// jsObj becomes - {name: 'a', other:'b'}
The JSON representation of above will look like:
var jsonString = "{'name': 'a', 'other':'b'}";
// will give you back jsObj.
var jsonObj = JSON.Parse(jsonString); // eval(jsonString) in older browsers
Note that you cannot have property without a name. This is not valid:
// invalid, will throw error
jsObj = { : 'a'};

Try an array that you push an item on to using
myArrayVar.push(value);
or
myArrayVar[myArrayVar.length] = value;

It makes no sense to have a property of an object without a property name. A "for ... in" loop is a loop over that collection of property names, after all. That is,
for (var k in obj)
will set "k" equal to each of the names of properties in "obj" in turn.

You cannot do this, because a JSON object is a collection of string-value pairs. A value can be an array, and you can push your object into that array, without an associative name.
http://www.json.org/

What you are describing is an array of objects.
var j = [{name:'a'},{name:'b'}];
This has the properties you are looking for. You can operate on it like so:
for(var i in j) {
alert(j[i].name);
}