June 2006
Intermediate to advanced
655 pages
18h 26m
English
Content preview from Ajax Design Patterns
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Chapter 18. Diagnosis
IF THERE’S ONE CERTAINTY IN THE LIFE OF A DEVELOPER, IT’S BUGS. AJAX PROGRAMMING ISN’T ROCKET science, but you can still expect the odd moment of pain during development and maybe even in production. Fortunately, there are plenty of techniques, tools, and libraries available to help you isolate problems as they arise. This chapter breaks them into four categories.
Logging is just good old logging applied to the browser, where log messages can be shown in a popup, uploaded to the server, or shown in some browser-specific way. Likewise, Debugging is general-purpose debugging applied to JavaScript that is running within the browser.
The next two patterns are more Ajax-specific. DOM Inspection is about analyzing the dynamic state of the DOM. Traffic Sniffing is about watching traffic between browser and server.
Logging
⊙ Capture, Log, Message, Monitor, Record
Figure 18-1. Logging
Developer Story
Dave’s search engine keeps giving a blank result for certain queries. Fortunately, he previously added some Logging commands to see how the query is processed, so he makes the console visible and sets log level to verbose. After entering the query again, he now sees that one of the regular expressions is not matching the query as expected.
Problem
How can you track program process?
Solution
Instrument your JavaScript with log
messages. Typically, the page contains a div element ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.