You can safely use the typeof operator on undefined variables. If it has been assigned any value, including null, typeof will return something other than undefined. typeof always returns a string. Therefore if (typeof maybeObject != “undefined”) { alert(“GOT THERE”); }
In the Developer Tools in Chrome, there is a bar along the top, called the Execution Context Selector (h/t felipe-sabino), just under the Elements tab, that changes depending on the context of the current tab. When in the Console tab there is a dropdown in that bar that allows you to select the frame context … Read more
A simple method: enable logging in recent versions of Requests (1.x and higher.) Requests uses the http.client and logging module configuration to control logging verbosity, as described here. Demonstration Code excerpted from the linked documentation: import requests import logging # These two lines enable debugging at httplib level (requests->urllib3->http.client) # You will see the REQUEST, … Read more
You can use built-in profiling support: after launching vim do :profile start profile.log :profile func * :profile file * ” At this point do slow actions :profile pause :noautocmd qall! (unlike quitting noautocmd is not really required, it just makes vim quit faster). Note: you won’t get information about functions there were deleted before vim … Read more
Before Java 5.0, use -Xdebug and -Xrunjdwp arguments. These options will still work in later versions, but it will run in interpreted mode instead of JIT, which will be slower. From Java 5.0, it is better to use the -agentlib:jdwp single option: -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=1044 Options on -Xrunjdwp or agentlib:jdwp arguments are : transport=dt_socket : means the … Read more
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I have module I use for situations like this – where a process will be running for a long time but gets stuck sometimes for unknown and irreproducible reasons. Its a bit hacky, and only works on unix (requires signals): import code, traceback, signal def debug(sig, frame): “””Interrupt running process, and provide a python prompt … Read more
Or you use the trick from PHP Debug to console. First you need a little PHP helper function function debug_to_console($data) { $output = $data; if (is_array($output)) $output = implode(‘,’, $output); echo “<script>console.log(‘Debug Objects: ” . $output . “‘ );</script>”; } Then you can use it like this: debug_to_console(“Test”); This will create an output like this: … Read more
Here’s an example of getting the stack via the traceback module, and printing it: import traceback def f(): g() def g(): for line in traceback.format_stack(): print(line.strip()) f() # Prints: # File “so-stack.py”, line 10, in <module> # f() # File “so-stack.py”, line 4, in f # g() # File “so-stack.py”, line 7, in g # … Read more
I had the same error message in Eclipse 3.4.1, SUN JVM1.6.0_07 connected to Tomcat 6.0 (running in debug-mode on a different machine, Sun JVM1.6.0_16, the debug connection did work correctly). Window –> Preferences –> Java –> Compiler –> Classfile Generation: “add line number attributes to generated class file” was checked. I did a clean, recompile. … Read more