count the number of rows in 2d array

Question

Description:

I am adding the data in my 2D array like the following

my_2d_array['user1'] = {'id':name,'socket':socket};
my_2d_array['user2'] = {'id':name,'socket':socket};

This 2D array keeps the record of all the connected users id and their respective sockets ... I want to display the number of users connected .. So far to do that would be to count the number of rows in the array and display it

I have tried following:

my_2d_array[].length; // this gives nothing 
my_2d_array.length; // this outputs 0 (as number)

What should I do to get the number of rows

UPDATE

I declared my array like this

var my_2d_array = [];

how did u declare your array? as array is index based.. so can you please tell us how did u declared it .. that can help us to tell u right and exact answer. — Deepak Sharma
– Deepak Sharma, Commented Dec 1, 2014 at 4:11

maček · Accepted Answer · 2014-12-01 04:13:13Z

6

This could work for you

// initialize
var my_2d_array = {};

// add users
my_2d_array["user1"] = ...
my_2d_array["user2"] = ...

// get number of users
Object.keys(my_2d_array).length;

//=> 2

You should consider using users instead of my_2d_array though. It communicates better and the actual data type is an Object, not specifically an Array.

answered Dec 1, 2014 at 4:13

maček

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Leo · Accepted Answer · 2014-12-01 04:13:07Z

3

Use push method

my_2d_array.push({'id':name,'socket':socket});
my_2d_array.push({'id':name,'socket':socket});

And my_2d_array.length to get the count

answered Dec 1, 2014 at 4:13

Leo

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5 Comments

maček Over a year ago

This changes the structure of his data though.

Rks Rock Over a year ago

u missed the key ... if I use your method where m I supposed to save the keys e.g did u mean this my_2d_array['user1'].push(...) ??

Leo Over a year ago

He updated his question, and it looks like he's not meant to use hash map.

Leo Over a year ago

@RksRock Are you new to JavaScript? If you are, then maybe you are using the wrong variable. Seems you want a hash map, which in JS usually implemented as objects ({}), not array ([]).

Leo Over a year ago

@RksRock In such case @maček gave a better answer, and you'd better declare var my_2d_array = {};, instead of [].

Alex · Accepted Answer · 2014-12-01 04:13:02Z

2

It looks like you are trying to figure out how many keys are in your javascript object my_2d_array.

You should be able to use Object.keys()

Here is a JsFiddle.

var my_2d_array = {};
var name = "Hello";
var socket = "World";
my_2d_array['user1'] = {'id':name,'socket':socket};

var name = "Hello2";
var socket = "World2";
my_2d_array['user2'] = {'id':name,'socket':socket};

alert( Object.keys(my_2d_array).length );

answered Dec 1, 2014 at 4:13

Alex

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