Tip 19: Use the browser's validation capabilities
Today's browsers provide support for advanced features such as XML, DHTML, Java applets, and remote Data services. Use these features whenever possible. All of these technologies can perform client-side validation and data caching, eliminating round-trip to the WEB server. If you are running a smart browser, the browser can do some validation for you (for example, check the credit card checksum for validity before performing the POST). Use this functionality whenever possible. Reducing the round-trip between the client and server reduces the load on the WEB server and reduces network traffic (although the first page sent to the browser may be larger) and any back-end resources that the server accesses. In addition, users do not have to read new pages as often as they do, so the user feels better. Doing so does not mean that you can not perform server-side validation-you should also always perform server-side validation. This prevents the client from generating the wrong data for some reason, such as a hacker, or the browser does not run a client-side validation routine. People have done a lot of work to develop "browser-independent" HTML. Because of this concern, developers are reluctant to use popular browser features, but these features could have improved performance. For some truly high-performance sites, you must be concerned about the browser "access" problem, a good strategy is to optimize the page to adapt to the popular browser. Browser functionality can be easily detected in ASP using the browser feature component. Tools such as Microsoft FrontPage help you design code that is appropriate for browsers and for the specified HTML version. See when Better worse? Weighing the Technology trade-offs to understand further discussion.
Tip 20: Avoid using string concatenation in circular statements
Many people create a string in a loop statement, as follows:
s =? <table>? & VbCrLf
For each fld in Rs. Fields
s = S &? <th>? & FLD. Name &?</th>?
Next
While not Rs. Eof
s = S & vbCrLf &? <tr>?
For each fld in Rs. Fields
s = S &? <td>? & FLD. Value &?</td>?
Next
s = S &? *lt;/tr>?
Rs. MoveNext
Wend
s = S & vbCrLf & </table>? & VbCrLf
Response.Write S
There are some problems with this approach. The first problem is that it takes two of times to repeat the string, and more generally, the time it takes to run the loop statement is proportional to the square of the number of records multiplied by the number of fields. You should consider using GetRows or GetString in specific cases where you convert an ADO recordset to an HTML table. If you are concatenating strings in JScript, it is particularly recommended to use the + = operator, that is, to use S + + to use a string instead of S = S +? A string?.
