Craig Condon
239 lines
9.5 KiB
HTML
239 lines
9.5 KiB
HTML
<!doctype html>
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<title>Debugger Node.js v0.8.14 Manual & Documentation</title>
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<li><a href="/" class="home">Home</a></li>
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<div id="column1" class="interior">
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<header>
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<h1>Node.js v0.8.14 Manual & Documentation</h1>
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<div id="gtoc">
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<p>
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<a href="index.html" name="toc">Index</a> |
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<a href="all.html">View on single page</a> |
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<a href="debugger.json">View as JSON</a>
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</p>
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</div>
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<hr>
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</header>
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<div id="toc">
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<h2>Table of Contents</h2>
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<ul>
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<li><a href="#debugger_debugger">Debugger</a><ul>
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<li><a href="#debugger_watchers">Watchers</a></li>
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<li><a href="#debugger_commands_reference">Commands reference</a><ul>
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<li><a href="#debugger_stepping">Stepping</a></li>
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<li><a href="#debugger_breakpoints">Breakpoints</a></li>
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<li><a href="#debugger_info">Info</a></li>
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<li><a href="#debugger_execution_control">Execution control</a></li>
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<li><a href="#debugger_various">Various</a></li>
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</ul>
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</li>
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<li><a href="#debugger_advanced_usage">Advanced Usage</a></li>
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</ul>
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</li>
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</ul>
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</div>
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<div id="apicontent">
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<h1>Debugger<span><a class="mark" href="#debugger_debugger" id="debugger_debugger">#</a></span></h1>
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<pre><code>Stability: 3 - Stable</code></pre>
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<!-- type=misc -->
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<p>V8 comes with an extensive debugger which is accessible out-of-process via a
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simple <a href="http://code.google.com/p/v8/wiki/DebuggerProtocol">TCP protocol</a>.
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Node has a built-in client for this debugger. To use this, start Node with the
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<code>debug</code> argument; a prompt will appear:
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</p>
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<pre><code>% node debug myscript.js
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< debugger listening on port 5858
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connecting... ok
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break in /home/indutny/Code/git/indutny/myscript.js:1
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1 x = 5;
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2 setTimeout(function () {
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3 debugger;
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debug></code></pre>
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<p>Node's debugger client doesn't support the full range of commands, but
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simple step and inspection is possible. By putting the statement <code>debugger;</code>
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into the source code of your script, you will enable a breakpoint.
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</p>
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<p>For example, suppose <code>myscript.js</code> looked like this:
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</p>
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<pre><code>// myscript.js
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x = 5;
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setTimeout(function () {
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debugger;
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console.log("world");
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}, 1000);
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console.log("hello");</code></pre>
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<p>Then once the debugger is run, it will break on line 4.
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</p>
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<pre><code>% node debug myscript.js
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< debugger listening on port 5858
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connecting... ok
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break in /home/indutny/Code/git/indutny/myscript.js:1
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1 x = 5;
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2 setTimeout(function () {
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3 debugger;
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debug> cont
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< hello
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break in /home/indutny/Code/git/indutny/myscript.js:3
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1 x = 5;
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2 setTimeout(function () {
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3 debugger;
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4 console.log("world");
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5 }, 1000);
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debug> next
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break in /home/indutny/Code/git/indutny/myscript.js:4
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2 setTimeout(function () {
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3 debugger;
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4 console.log("world");
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5 }, 1000);
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6 console.log("hello");
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debug> repl
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Press Ctrl + C to leave debug repl
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> x
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5
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> 2+2
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4
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debug> next
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< world
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break in /home/indutny/Code/git/indutny/myscript.js:5
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3 debugger;
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4 console.log("world");
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5 }, 1000);
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6 console.log("hello");
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7
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debug> quit
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%</code></pre>
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<p>The <code>repl</code> command allows you to evaluate code remotely. The <code>next</code> command
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steps over to the next line. There are a few other commands available and more
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to come. Type <code>help</code> to see others.
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</p>
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<h2>Watchers<span><a class="mark" href="#debugger_watchers" id="debugger_watchers">#</a></span></h2>
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<p>You can watch expression and variable values while debugging your code.
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On every breakpoint each expression from the watchers list will be evaluated
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in the current context and displayed just before the breakpoint's source code
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listing.
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</p>
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<p>To start watching an expression, type <code>watch("my_expression")</code>. <code>watchers</code>
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prints the active watchers. To remove a watcher, type
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<code>unwatch("my_expression")</code>.
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</p>
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<h2>Commands reference<span><a class="mark" href="#debugger_commands_reference" id="debugger_commands_reference">#</a></span></h2>
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<h3>Stepping<span><a class="mark" href="#debugger_stepping" id="debugger_stepping">#</a></span></h3>
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<ul>
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<li><code>cont</code>, <code>c</code> - Continue execution</li>
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<li><code>next</code>, <code>n</code> - Step next</li>
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<li><code>step</code>, <code>s</code> - Step in</li>
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<li><code>out</code>, <code>o</code> - Step out</li>
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<li><code>pause</code> - Pause running code (like pause button in Developer TOols)</li>
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</ul>
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<h3>Breakpoints<span><a class="mark" href="#debugger_breakpoints" id="debugger_breakpoints">#</a></span></h3>
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<div class="signature"><ul>
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<li><code>setBreakpoint()</code>, <code>sb()</code> - Set breakpoint on current line</li>
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<li><code>setBreakpoint(line)</code>, <code>sb(line)</code> - Set breakpoint on specific line</li>
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<li><code>setBreakpoint('fn()')</code>, <code>sb(...)</code> - Set breakpoint on a first statement in
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functions body</li>
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<li><code>setBreakpoint('script.js', 1)</code>, <code>sb(...)</code> - Set breakpoint on first line of
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script.js</li>
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<li><code>clearBreakpoint</code>, <code>cb(...)</code> - Clear breakpoint</li>
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</div></ul>
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<h3>Info<span><a class="mark" href="#debugger_info" id="debugger_info">#</a></span></h3>
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<div class="signature"><ul>
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<li><code>backtrace</code>, <code>bt</code> - Print backtrace of current execution frame</li>
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<li><code>list(5)</code> - List scripts source code with 5 line context (5 lines before and
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after)</li>
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<li><code>watch(expr)</code> - Add expression to watch list</li>
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<li><code>unwatch(expr)</code> - Remove expression from watch list</li>
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<li><code>watchers</code> - List all watchers and their values (automatically listed on each
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breakpoint)</li>
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<li><code>repl</code> - Open debugger's repl for evaluation in debugging script's context</li>
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</div></ul>
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<h3>Execution control<span><a class="mark" href="#debugger_execution_control" id="debugger_execution_control">#</a></span></h3>
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<div class="signature"><ul>
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<li><code>run</code> - Run script (automatically runs on debugger's start)</li>
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<li><code>restart</code> - Restart script</li>
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<li><code>kill</code> - Kill script</li>
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</div></ul>
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<h3>Various<span><a class="mark" href="#debugger_various" id="debugger_various">#</a></span></h3>
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<div class="signature"><ul>
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<li><code>scripts</code> - List all loaded scripts</li>
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<li><code>version</code> - Display v8's version</li>
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</div></ul>
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<h2>Advanced Usage<span><a class="mark" href="#debugger_advanced_usage" id="debugger_advanced_usage">#</a></span></h2>
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<p>The V8 debugger can be enabled and accessed either by starting Node with
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the <code>--debug</code> command-line flag or by signaling an existing Node process
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with <code>SIGUSR1</code>.
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</p>
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</div>
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<p>Copyright <a href="http://joyent.com/">Joyent, Inc</a>, Node.js is a <a href="/trademark-policy.pdf">trademark</a> of Joyent, Inc. View <a href="https://raw.github.com/joyent/node/v0.8.14/LICENSE">license</a>.</p>
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