javascript - Creating a variable, with a variable in an each loop - jQuery - Stack Overflow

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I'm having some difficulty creating a variable with another variable in jQuery. I don't know how to write the var side of the equation. Here's what I'm trying to create:

var $counter= 0;
    $('.selector').each(function(){
       $counter += 1;
       var newVariable-($counter) // this is where I'd like to create the new  
                                  // variable with the number from $counter at the end.
    });

with the goal to creating:

newVariable-1
newVariable-2
newVariable-3... 

and so on...

I'm having some difficulty creating a variable with another variable in jQuery. I don't know how to write the var side of the equation. Here's what I'm trying to create:

var $counter= 0;
    $('.selector').each(function(){
       $counter += 1;
       var newVariable-($counter) // this is where I'd like to create the new  
                                  // variable with the number from $counter at the end.
    });

with the goal to creating:

newVariable-1
newVariable-2
newVariable-3... 

and so on...

• javascript
• jquery
• variables
• dynamic
• each

Share Improve this question Follow edited Jun 13, 2014 at 4:42 ngrashia 9,90455 gold badges4444 silver badges5858 bronze badges asked Jun 13, 2014 at 4:35 user3717403user3717403 4311 gold badge11 silver badge44 bronze badges 2

• 1 stackoverflow./questions/2895930/… – CRABOLO Commented Jun 13, 2014 at 4:38
• Readability tip: Try to use variables beginning with $ only for caching jQuery selections. (var $counter = $('#counter'); var counter = 0;) – christian314159 Commented Jun 13, 2014 at 4:41

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3 Answers 3

Sorted by: Reset to default 8

You could create an object to hold these values but not dynamic variables.

var $counter= 0;
var variableHolder = {};
$('.selector').each(function(){
   $counter += 1;
   variableHolder["newVariable-"+$counter] = ...
});

Or if you want to make global variables (which is not remended), you could use window:

var $counter= 0;
$('.selector').each(function(){
   $counter += 1;
   window["newVariable-"+$counter] = ...
});

As others have pointed out, using an {} with square bracket notation will simplify this task greatly.

Something like this:

var myobj = {},
    prefix = 'my_cool_var';

for(var i = 0, len = 10; i < len; i++) {
    myobj[prefix + i] = undefined; // { my_cool_var + i : undefined }
}

// Setters - dot notation and square bracket
myobj.my_cool_var1 = "Hello!";
myobj['my_cool_var2'] = "Hello 2!";

// Getters - dot notation and square bracket
alert(myobj.my_cool_var1); // alerts Hello!
alert(myobj['my_cool_var2']); // alerts Hello 2!

Now, if you needed to expose the variables in a global scope (yuck - but hey, sometimes you gotta) so you don't need to specify an object (myobj), you can use window with square bracket notation in your for loop.

var prefix = 'my_global_var';

for(var i = 0, len = 10; i < len; i++) {
    window[prefix + i] = undefined; // creates global, my_global_var + i = undefined
}

my_cool_var1 = "Hello!";
alert(my_cool_var1); // alerts Hello!

Finally, if you search the web deep enough, you'll find eval examples like this:

var prefix = 'my_evil_var';

for(var i = 0, len = 10; i < len; i++) {
    // Don't do this. Use square bracket notation with window, if you need a global.
    eval(prefix + i + '= undefined') // creates global, my_evil_var + i = undefined
}

my_evil_var = "Eval abuse is bad!!";
alert(my_evil_var1); // alerts Eval abuse is bad!!

Hope this helps!

Just make use of the json in this context,

var $counter= 0;
var $newVar = {};

$('.selector').each(function(){
   $counter += 1;
   $newVar['newVariable-'+ ($counter)] = null;
});

so you can access it like $newVar.newVariable-1,.. $newVar.newVariable-N And please note that this is the best practice, we could do as you asked by accessing the window object, but that is not remended.

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