Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.javascript > #23553

Re: arr.push(obj);

Show all headers | View raw

Christoph Michael Becker wrote:

> jonas.thornvall@gmail.com wrote:
>> I try to get the gist of what you saying but for me it is all very
>> confusing. Do you mean something like this?
>> 
>> var arr = new Array();
>> for (var i = -500; i <= +500; i ++ )
>> {
>> arr[i] =
>>    {
>>       count : i,
>>       fcolor : 'black',
>>       rheight : 100,
>>       rwidth : 100,
>>       rcolor : 'white'
>>    }
>> }
> 
> Yes.  If you prefer, you can use another variable to store the object
> first, e.g.:
> 
>   {
>     var obj = {...};
>     arr[i] = obj;
>   }

It is not possible to store objects in variables/properties.  It is only 
possible to store *references to* objects.  References are values.  The 
difference is important because it emphasizes that there can be several 
references to the same object, and there can be unnamed references. [0]
In short: Objects have identity, not name.

The above Block statement is equivalent to

  var obj;

  {
    obj = {...};
    arr[i] = obj;
  }

which means:

1. Declare a (here: local) variable named “obj”.  (This happens *before*
   control enters the Block statement, even before all other statements in
   that local context are executed.) [1]

2. Create an Object instance, initialize it with the specified properties,
   and return a reference to it (“return” with regard to the algorithm only;
   understood as the *evaluation value*). [2]

3. Assign to “obj” the reference to the newly created object. [3]

4. Retrieve the reference to the newly created object from “obj” [4] and
   store it in (copy it to) the property of the object referred to by “arr”
   that is specified by the value of “i” converted to String.  (Create
   the property if it does not exist and their are no provisions to creating
   it. [5]  If “arr” is referring to an Array instance, modify the
   value of its “length” property value if the value of “i” is an index
   value and the value of “i” converted to String, then converted to
   unsigned 32-bit integer, is greater than the last index in the array.
   [6])

5. Set the evaluation value of the Block statement to “obj” because it is
   the evaluation value of the assignment, which is the last statement
   in the Block. [7]

_______
[0] <http://ecma-international.org/ecma-262/5.1/#sec-4.2.1>
[1] <http://ecma-international.org/ecma-262/5.1/#sec-12.2>
[2] <http://ecma-international.org/ecma-262/5.1/#sec-11.1.5>
[3] <http://ecma-international.org/ecma-262/5.1/#sec-11.13.1>
[4] <http://ecma-international.org/ecma-262/5.1/#sec-10.3.1>
[5] <http://ecma-international.org/ecma-262/5.1/#sec-8.7.2>
[6] <http://ecma-international.org/ecma-262/5.1/#sec-15.4.5.1>
[7] <http://ecma-international.org/ecma-262/5.1/#sec-12.1>
-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

Back to comp.lang.javascript | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 17:38 -0700
  Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 20:19 -0700
    Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 20:28 -0700
      Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-10 21:19 -0700
        Re: arr.push(obj); Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-03-11 06:59 -0300
          Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 16:02 +0100
            Re: arr.push(obj); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-11 16:22 +0000
            Re: arr.push(obj); Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-03-11 13:32 -0300
  Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-11 10:21 +0100
    Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 03:53 -0700
      Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-11 14:03 +0100
        Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 07:45 -0700
          Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-11 16:24 +0100
            Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 10:40 -0700
              Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 10:51 -0700
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 19:23 +0100
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 15:33 -0700
                Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-12 00:37 +0100
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 16:46 -0700
                Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-12 01:05 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 01:40 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 00:48 +0100
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 15:43 -0700
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 16:18 -0700
                Re: arr.push(obj); "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-03-12 00:39 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 00:52 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 00:49 +0100
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 17:16 -0700
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 02:07 +0100
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 18:13 -0700
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-13 02:25 +0100
                Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-13 11:03 +0100
                Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-12 07:46 -0700
                Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-12 01:27 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 01:44 +0100
          Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 16:26 +0100
            Re: arr.push(obj); Carlos Pedro <carlospedr@gmail.com> - 2014-03-11 09:21 -0700
            Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-11 18:01 +0100
              Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-11 19:15 +0100
                Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-11 20:32 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 01:01 +0100
                Re: arr.push(obj); Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-03-12 04:08 +0100
                Re: arr.push(obj); Christoph Michael Becker <cmbecker69@arcor.de> - 2014-03-12 18:00 +0100
  Re: arr.push(obj); Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-03-11 06:24 -0300
    Re: arr.push(obj); jonas.thornvall@gmail.com - 2014-03-11 03:47 -0700
      Re: arr.push(obj); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-11 15:19 +0000

csiph-web