Difference between revisions of "Tutorials webOS Debugging 101"
m (Fixed some punctuation and spelling. Added <code> tags to commands that are to be issued in PuTTY.) |
m (Added logging options for JSON values.) |
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Add mojo.logs to your code and evaluate them in putty. | Add mojo.logs to your code and evaluate them in putty. | ||
| − | Mojo.Log.error("****V" + " my variable: " + this.variable ); | + | Mojo.Log.error("****V" + " my variable: " + this.variable ); |
| + | Alternatively you can use Mojo.Log.error("my JSON variable: %j", this.jsonObject); or Mojo.Log.error("my JSON variable: "+ JSON.stringify(this.jsonObject)); to log JSON Objects. | ||
putty.exe | putty.exe | ||
| Line 16: | Line 17: | ||
<p>no password just hit enter</p> | <p>no password just hit enter</p> | ||
| − | <p>type: <code> | + | <p>type: <code>grep payment /var/log/messages</code></p> |
<p>"payment" is the string you are searching for with grep</p> | <p>"payment" is the string you are searching for with grep</p> | ||
| Line 23: | Line 24: | ||
<p>Mojo.Log.error writes to /var/log/messages</p> | <p>Mojo.Log.error writes to /var/log/messages</p> | ||
| − | + | <p>grep: searches for the string following grep within the file specified after the search string, and prints out those lines</p> | |
| − | <p>grep: searches | ||
| − | |||
<p>SIDE NOTE: if you copy text into the clipboard, you can paste it into putty by right-clicking in putty.</p> | <p>SIDE NOTE: if you copy text into the clipboard, you can paste it into putty by right-clicking in putty.</p> | ||
Latest revision as of 15:29, 25 July 2011
If your results are not what you expected, use JavaScript's try/catch/finally block statements to localize the problem. The first thing you want to do is get as close as possible to where you believe the error is occurring. If you're not sure where, start at the beginning.
Add mojo.logs to your code and evaluate them in putty.
Mojo.Log.error("****V" + " my variable: " + this.variable );
Alternatively you can use Mojo.Log.error("my JSON variable: %j", this.jsonObject); or Mojo.Log.error("my JSON variable: "+ JSON.stringify(this.jsonObject)); to log JSON Objects.
putty.exe (for emulator)
ip address "localhost" port 5522
connection type: ssh
when command line opens, type root
no password just hit enter
type: grep payment /var/log/messages
"payment" is the string you are searching for with grep
after you log in to putty:
Mojo.Log.error writes to /var/log/messages
grep: searches for the string following grep within the file specified after the search string, and prints out those lines
SIDE NOTE: if you copy text into the clipboard, you can paste it into putty by right-clicking in putty.