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doc: improvements to debugger.markdown copy

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General improvements to debugger.markdown

PR-URL: https://github.com/nodejs/node/pull/4436
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Minwoo Jung <jmwsoft@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
This commit is contained in:
James M Snell 2015-12-26 21:19:35 -08:00
parent 8ac1ff73fb
commit 1a004f1187
1 changed files with 31 additions and 27 deletions
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doc/api/debugger.markdown
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@ -4,9 +4,10 @@
<!-- type=misc -->
V8 comes with an extensive debugger which is accessible out-of-process via a
simple [TCP protocol][]. Node.js has a built-in client for this debugger. To
use this, start Node.js with the `debug` argument; a prompt will appear:
Node.js includes a full-featured out-of-process debugging utility accessible
via a simple [TCP-based protocol][] and built-in debugging client. To use it,
start Node.js with the `debug` argument followed by the path to the script to
debug; a prompt will be displayed indicating successful launch of the debugger:
% node debug myscript.js
< debugger listening on port 5858
@ -17,11 +18,13 @@ use this, start Node.js with the `debug` argument; a prompt will appear:
3 debugger;
debug>
Node.js's debugger client doesn't support the full range of commands, but
simple step and inspection is possible. By putting the statement `debugger;`
into the source code of your script, you will enable a breakpoint.
Node.js's debugger client does not yet support the full range of commands, but
simple step and inspection are possible.
For example, suppose `myscript.js` looked like this:
Inserting the statement `debugger;` into the source code of a script will
enable a breakpoint at that position in the code.
For example, suppose `myscript.js` is written as:
// myscript.js
x = 5;
@ -31,7 +34,7 @@ For example, suppose `myscript.js` looked like this:
}, 1000);
console.log('hello');
Then once the debugger is run, it will break on line 4.
Once the debugger is run, a breakpoint will occur at line 4:
% node debug myscript.js
< debugger listening on port 5858
@ -73,20 +76,20 @@ Then once the debugger is run, it will break on line 4.
%
The `repl` command allows you to evaluate code remotely. The `next` command
steps over to the next line. There are a few other commands available and more
to come. Type `help` to see others.
The `repl` command allows code to be evaluated remotely. The `next` command
steps over to the next line. Type `help` to see what other commands are
available.
## Watchers
You can watch expression and variable values while debugging your code.
On every breakpoint each expression from the watchers list will be evaluated
in the current context and displayed just before the breakpoint's source code
listing.
It is possible to watch expression and variable values while debugging. On
every breakpoint, each expression from the watchers list will be evaluated
in the current context and displayed immediately before the breakpoint's
source code listing.
To start watching an expression, type `watch("my_expression")`. `watchers`
prints the active watchers. To remove a watcher, type
`unwatch("my_expression")`.
To begin watching an expression, type `watch('my_expression')`. The command
`watchers` will print the active watchers. To remove a watcher, type
`unwatch('my_expression')`.
## Commands reference
@ -154,19 +157,20 @@ breakpoint)
### Various
* `scripts` - List all loaded scripts
* `version` - Display v8's version
* `version` - Display V8's version
## Advanced Usage
The V8 debugger can be enabled and accessed either by starting Node.js with
the `--debug` command-line flag or by signaling an existing Node.js process
with `SIGUSR1`.
An alternative way of enabling and accessing the debugger is to start
Node.js with the `--debug` command-line flag or by signaling an existing
Node.js process with `SIGUSR1`.
Once a process has been set in debug mode with this it can be connected to
with the Node.js debugger. Either connect to the `pid` or the URI to the
debugger. The syntax is:
Once a process has been set in debug mode this way, it can be connected to
using the Node.js debugger by either connecting to the `pid` of the running
process or via URI reference to the listening debugger:
* `node debug -p <pid>` - Connects to the process via the `pid`
* `node debug <URI>` - Connects to the process via the URI such as localhost:5858
* `node debug <URI>` - Connects to the process via the URI such as
localhost:5858
[TCP protocol]: https://github.com/v8/v8/wiki/Debugging-Protocol
[TCP-based protocol]: https://github.com/v8/v8/wiki/Debugging-Protocol