Debugging rails with ruby-debug

1. setup
$> sudo gem install ruby-debug

2. start rails webrick/mongrel web server
$> script/server --debugger

3. using debugger in controller

class PeopleController < ApplicationController def new debugger # 当应用程序访问到此行时，在console中会出现debugger控制台 @person = Person.new end end

4. debugger shell 命令帮助

(rdb:40) help
ruby-debug help v0.10.3
Type 'help ' for help on a specific command

Available commands:
backtrace delete enable help next quit show
break disable eval info p reload source
catch display exit irb pp restart step
condition down finish list ps save thread
continue edit frame method putl set trace

其中比较常用的是next/list/continue/method/backtrace命令。

更多关于ruby-debug，查看以下链接：
http://articles.sitepoint.com/article/debug-rails-app-ruby-debug
http://guides.rubyonrails.org/debugging_rails_applications.html

Javascript Debugger functions

<script type="text/javascript" charset="utf-8">
 // Helper function to parse out the name from the text of the function
 function getFunctionName(f) 
 {
   if (/function (\w+)/.test(String(f)))
     return RegExp.$1;
   else
     return "";
 }

 // Manually piece together a stack trace using the caller property
 function constructStackTrace(f) 
 {
   if (!f)
     return "";

   var thisRecord = getFunctionName(f) + "(";

   for (var i=0; i< f.arguments.length; i++) {
     thisRecord += String(f.arguments[i]);
     // add a comma if this isn’t the last argument
     if (i+1 < f.arguments.length)
       thisRecord += ", ";
   }

   return thisRecord + ")\n" + constructStackTrace(f.caller);
 }

 // Retrieve a stack trace. Works in Mozilla and IE.
 function getStackTrace() {
   var err = new Error;
   // if stack property exists, use it; else construct it manually
   if (err.stack)
     return err.stack;
   else
/*  alert(getStackTrace.caller);*/
     return constructStackTrace(getStackTrace.caller);
 }

 function a(x) 
 {
   document.writeln(x);
   document.writeln("<br/>\n----Stack trace below----\n<br/>");
   document.writeln(getStackTrace());
/*   document.writeln((new Error).stack);*/
 }
 function b(x) {
   a(x+1);
 }
 function c(x) {
   b(x+1);
 }
 c(10);
</script>