Chapter 51. Application: A Poor Man's Order Form


  • Live math on table rows and columns

  • Number formatting

  • Code reusability

I hesitate to call the application described in this chapter an order form because it is not in any way intended for use as a client-side shopping cart or some of the more advanced e-commerce applications you see on the Web. No, the goal here is to demonstrate how JavaScript can be used to assist users with column-and-row arithmetic, very much like the kinds of arithmetic needed to calculate the total for an order of goods.

Although this order form is not linked to any particular online catalog, some or all of it can be used as a piece for a small e-commerce site. The form in the example here requires that users input product descriptions and prices, but there is no reason that a client-side JavaScript shopping cart can't accumulate the shopper's choices from catalog pages, and then present them in an order form with product descriptions and prices hard-wired into the table. There still are entry boxes for quantity and selecting local sales tax rates. But all the arithmetic products and sums are calculated quickly on the client with JavaScript.

Along the way, you should also discover how to design code—more specifically, JavaScript data structures—in such a way that they are easily editable by non-scripters who are responsible for updating the embedded data. Therefore, even if you prefer to leave professional e-commerce order processing to server applications, ...

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