Alerting Javascript array object shows empty

Question

I am trying to send the JavaScript array to my php, but php gets empty [].
It even shows like that in my browser. I have always sent JSON and had no problem, but now have this format.

I have this example that makes no sense...it's just a code to illustrate the issue:

var blah    = [];
var letters = ['a', 'b', 'c', 'd'];

for (var i = 0; i < letters.length; i++)
{
    blah[letters[i]] = i;
}

Inside firebug DOM it shows as follows:

blah      []
    a      0
    b      1
    c      2
    d      3

When I do

alert(blah) ------------------------------- I get empty
alert(JSON.stringify(blah)) ----- I get []
alert(blah.a) ---------------------------- I get 0

So how can I pass this object to php? Thanks

Thank you for the answers and efforts. rossipedia answered first so I will accept his answer. Appreciate it — Brian
– Brian, Commented Jul 8, 2013 at 6:18

rossipedia · Accepted Answer · 2013-07-08 06:02:36Z

6

Instead of an array, try using an object.

So instead of:

var blah    = [];

Try

var blah    = {};

answered Jul 8, 2013 at 6:02

rossipedia

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2 Comments

Brian Over a year ago

that example is only for illustration sake

rossipedia Over a year ago

Removed the example from my answer. The issue is that you're using an array when you should be using an object.

deceze · Accepted Answer · 2013-07-08 06:02:46Z

4

Arrays are continuously numerically indexed. They do not have strings as key names.
What you want is an object {}, not an array [].

answered Jul 8, 2013 at 6:02

deceze♦

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Comments

Zaheer Ahmed · Accepted Answer · 2013-07-08 06:10:16Z

2

Can not assign key value collection in array. You need to work on objects:

var obj = {
    key1: value1,
    key2: value2
};

for converting array to string you can use:

var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.toString();

with seperator:

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var energy = fruits.join(" and ");

Here is working Demo

try this:

var blah    = {};
var letters = ['a', 'b', 'c', 'd'];

for (var i = 0; i < letters.length; i++)
{
    blah[letters[i]] = i;
}

alert(JSON.stringify(blah));

answered Jul 8, 2013 at 6:10

Zaheer Ahmed

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1 Comment

Brian Over a year ago

but what if my key is a variable, how should i assign then? Like this fruits[key] = value?

mohkhan · Accepted Answer · 2013-07-08 06:06:55Z

1

I have answered this before. Anyway, blah is an array, but you are not using it as array, you are using it as a hashmap. Arrays work with indexes and maps work with keys. Any object in JS can also act like a map. For e.g

var obj = new Object();
obj.a = 10;
obj["b"] = 20;

var obj2 = function(){...}
obj2.foo = 10;
obj2.bar = "baz";

Similarly, Array is also and Object and can act like a map. But when you use the array like a map, its array is not utilized to store the elements. They just act like above. So the length of an Array is 0 even though it has properties attached to it.

What you must do is use Array methods like push and pop to populate and retrieve from it.

answered Jul 8, 2013 at 6:06

mohkhan

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