[jQuery Help] Scan or enter barcode and add to table but count duplicate entries.

[jQuery Help] Scan or enter barcode and add to table but count duplicate entries.

Hi all,

/* -- BACKGROUND -- */
I work for a company in the retail sector and I have been developing a website for said company. I am currently working on a second site for only staff to use using the WordPress blog/CMS system. 

Creating plugins for WordPress I can get my head round but jQuery not so much.

/* -- MY IDEA -- */ 
My Idea is to have a permanently focused input field where a bar code can be scanned in via a bar code scanner or can me manually entered. Switching between being scanned or manually entered I can do with jQuery.

Once the bar code has be entered/scanned I want it to be added to a table just consisting of two columns, Bar code and Count/QTY.

In due time I can learn to append a table row with data which has been entered.

/* -- QUESTION -- */
Is there a way jQuery can detect a duplicate entry and add it to the Count/QTY and if so how would I go about implementing said feature.

/* -- EXAMPLE -- */

+ BARCODE - QTY +
+                  -         +
+ Entry A      -    1   +
+ Entry B      -    1   +
+ Entry A      -    1   +
+ Entry A      -    1   +
+ -------------------------- +


TO

+ BARCODE - QTY +
+                  -         +
+ Entry A      -    3   +
+ Entry B      -    1   +
+ -------------------------- +

Any help or input will be greatly appreciated.

Stephen