question about enabling attributes

[tombo9876]

I have a bit of a problem. The store I'm setting up sells audio cables. There are 4 set lengths that the prices are determined for. The lengths are .5, 1, 1.5, and 2 meters. However, if the customer wants more than 2 meters, there is an addition price of $X per half meter. As of now, I have it set up to where if the customer would like a 4 meter cable, they choose 2 meters from the preset lengths ( a drop down box), and enter 2 in a text box which I have labeled "Additional meters if needed". It works, but its not what the owner of the company wants. He would like me to add another option in the drop down box for 2+ meters, and then the customer would enter the total length in the text box. I can code the calculation of the price, no problem. However, I only want the text box to be enabled if the customer chooses the 2+ meter option. I know you can disable and enable text boxes on the fly with javascript, but I do not know how, or if its even possible to do this with a text box on a product page. Any insight would be greatly appreciated! Thanks

[tombo9876]

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