Debugger

The Palm debugger is a command-line tool on the Palm® webOS™ platform device or emulator that enables you to use breakpoints, display variables, and trace the stack.

Note:

If you connect the debugger while the emulator is still booting, the emulator may take longer to boot because the debugger imposes a performance penalty which slows down the booting process. The debugger will not break in native non-JS code and some system JS code. During the booting process, the system may not always be executing breakable JS code. While the emulator is still booting, the system might not always respond immediately to a break request.

Starting the Debugger

This section describes how to start the debugger and defines the following command types:

Basic
Breakpoints
Execution
Source
Program Stack
Variables

Using the Debugger

Follow these steps:

Open a terminal to the device (either novaterm or ssh).
Type debug to start the debugger, and then press Enter once to get the dbg> prompt.

Basic Commands

Command	Description
help	Shows the available commands.
scripts	Shows all of the loaded scripts, including the Palm® Mojo™ SDK framework.

Breakpoints

Command	Description
break script:line or b script:line	Sets a breakpoint. Specify the full path to the script, and the line number. Example: b /var/usr/palm/applications/com.yourdomain.test/app/assistants/stage-assistant.js:5
clear ID or delete ID or d ID	Clears the breakpoint specified by ID.
cond ID expression	Makes the breakpoint specified by ID conditional on an expression. The expression is any boolean JavaScript expression that can be evaluated at the site of the breakpoint. If the expression evaluates to true, the breakpoint triggers. To make the breakpoint unconditional again, type cond ID with no expression.
disable ID or dis ID	Disables the breakpoint specified by ID.
enable ID or en ID	Enables the breakpoint specified by ID.
ignore ID [count]	Ignores the breakpoint specified by ID ( count times, if specified).
info break or inf br	Shows the current breakpoints and their ID numbers.

Execution Control

Command	Description
continue or c	Continue (run).
finish or fin	Step out of the current method.
next or n	Step over.
step or s	Step into.

Program Stack

Command	Description
backtrace or bt	Shows the call stack.
down or do	Moves down one frame in the call stack listing.
frame number or f number	Goes to the frame number in the call stack listing. If a number is not specified, displays the current frame.
up	Moves up one frame in the call stack listing.

Source

Command	Description
list or l	Shows the next 10 lines of code.
list - or l -	Shows the previous 10 lines of code.
list first, last	Shows from line first to line last.

Variables

Command	Description
info args or inf ar	Displays the arguments.
info locals or inf lo	Displays the values of local variables.
print expression or p expression	Executes expression and displays the result. For example, expression might be a variable from the script.
set variable = expression	Sets variable to expression.

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