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<h1>Node.js v0.10.25 Manual & Documentation</h1>
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<h2>Table of Contents</h2>
<ul>
<li><a href="#readline_readline">Readline</a><ul>
<li><a href="#readline_readline_createinterface_options">readline.createInterface(options)</a></li>
<li><a href="#readline_class_interface">Class: Interface</a><ul>
<li><a href="#readline_rl_setprompt_prompt_length">rl.setPrompt(prompt, length)</a></li>
<li><a href="#readline_rl_prompt_preservecursor">rl.prompt([preserveCursor])</a></li>
<li><a href="#readline_rl_question_query_callback">rl.question(query, callback)</a></li>
<li><a href="#readline_rl_pause">rl.pause()</a></li>
<li><a href="#readline_rl_resume">rl.resume()</a></li>
<li><a href="#readline_rl_close">rl.close()</a></li>
<li><a href="#readline_rl_write_data_key">rl.write(data, [key])</a></li>
</ul>
</li>
<li><a href="#readline_events">Events</a><ul>
<li><a href="#readline_event_line">Event: 'line'</a></li>
<li><a href="#readline_event_pause">Event: 'pause'</a></li>
<li><a href="#readline_event_resume">Event: 'resume'</a></li>
<li><a href="#readline_event_close">Event: 'close'</a></li>
<li><a href="#readline_event_sigint">Event: 'SIGINT'</a></li>
<li><a href="#readline_event_sigtstp">Event: 'SIGTSTP'</a></li>
<li><a href="#readline_event_sigcont">Event: 'SIGCONT'</a></li>
</ul>
</li>
<li><a href="#readline_example_tiny_cli">Example: Tiny CLI</a></li>
</ul>
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<div id="apicontent">
<h1>Readline<span><a class="mark" href="#readline_readline" id="readline_readline">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable</pre><p>To use this module, do <code>require('readline')</code>. Readline allows reading of a
stream (such as <code>process.stdin</code>) on a line-by-line basis.
</p>
<p>Note that once you've invoked this module, your node program will not
terminate until you've closed the interface. Here's how to allow your
program to gracefully exit:
</p>
<pre><code>var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
rl.question("What do you think of node.js? ", function(answer) {
// TODO: Log the answer in a database
console.log("Thank you for your valuable feedback:", answer);
rl.close();
});</code></pre>
<h2>readline.createInterface(options)<span><a class="mark" href="#readline_readline_createinterface_options" id="readline_readline_createinterface_options">#</a></span></h2>
<p>Creates a readline <code>Interface</code> instance. Accepts an "options" Object that takes
the following values:
</p>
<ul>
<li><p><code>input</code> - the readable stream to listen to (Required).</p>
</li>
<li><p><code>output</code> - the writable stream to write readline data to (Required).</p>
</li>
<li><p><code>completer</code> - an optional function that is used for Tab autocompletion. See
below for an example of using this.</p>
</li>
<li><p><code>terminal</code> - pass <code>true</code> if the <code>input</code> and <code>output</code> streams should be
treated like a TTY, and have ANSI/VT100 escape codes written to it.
Defaults to checking <code>isTTY</code> on the <code>output</code> stream upon instantiation.</p>
</li>
</ul>
<p>The <code>completer</code> function is given a the current line entered by the user, and
is supposed to return an Array with 2 entries:
</p>
<ol>
<li><p>An Array with matching entries for the completion.</p>
</li>
<li><p>The substring that was used for the matching.</p>
</li>
</ol>
<p>Which ends up looking something like:
<code>[[substr1, substr2, ...], originalsubstring]</code>.
</p>
<p>Example:
</p>
<pre><code>function completer(line) {
var completions = '.help .error .exit .quit .q'.split(' ')
var hits = completions.filter(function(c) { return c.indexOf(line) == 0 })
// show all completions if none found
return [hits.length ? hits : completions, line]
}</code></pre>
<p>Also <code>completer</code> can be run in async mode if it accepts two arguments:
</p>
<pre><code>function completer(linePartial, callback) {
callback(null, [['123'], linePartial]);
}</code></pre>
<p><code>createInterface</code> is commonly used with <code>process.stdin</code> and
<code>process.stdout</code> in order to accept user input:
</p>
<pre><code>var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});</code></pre>
<p>Once you have a readline instance, you most commonly listen for the
<code>"line"</code> event.
</p>
<p>If <code>terminal</code> is <code>true</code> for this instance then the <code>output</code> stream will get
the best compatibility if it defines an <code>output.columns</code> property, and fires
a <code>"resize"</code> event on the <code>output</code> if/when the columns ever change
(<code>process.stdout</code> does this automatically when it is a TTY).
</p>
<h2>Class: Interface<span><a class="mark" href="#readline_class_interface" id="readline_class_interface">#</a></span></h2>
<p>The class that represents a readline interface with an input and output
stream.
</p>
<h3>rl.setPrompt(prompt, length)<span><a class="mark" href="#readline_rl_setprompt_prompt_length" id="readline_rl_setprompt_prompt_length">#</a></span></h3>
<p>Sets the prompt, for example when you run <code>node</code> on the command line, you see
<code>> </code>, which is node's prompt.
</p>
<h3>rl.prompt([preserveCursor])<span><a class="mark" href="#readline_rl_prompt_preservecursor" id="readline_rl_prompt_preservecursor">#</a></span></h3>
<p>Readies readline for input from the user, putting the current <code>setPrompt</code>
options on a new line, giving the user a new spot to write. Set <code>preserveCursor</code>
to <code>true</code> to prevent the cursor placement being reset to <code>0</code>.
</p>
<p>This will also resume the <code>input</code> stream used with <code>createInterface</code> if it has
been paused.
</p>
<h3>rl.question(query, callback)<span><a class="mark" href="#readline_rl_question_query_callback" id="readline_rl_question_query_callback">#</a></span></h3>
<p>Prepends the prompt with <code>query</code> and invokes <code>callback</code> with the user's
response. Displays the query to the user, and then invokes <code>callback</code>
with the user's response after it has been typed.
</p>
<p>This will also resume the <code>input</code> stream used with <code>createInterface</code> if
it has been paused.
</p>
<p>Example usage:
</p>
<pre><code>interface.question('What is your favorite food?', function(answer) {
console.log('Oh, so your favorite food is ' + answer);
});</code></pre>
<h3>rl.pause()<span><a class="mark" href="#readline_rl_pause" id="readline_rl_pause">#</a></span></h3>
<p>Pauses the readline <code>input</code> stream, allowing it to be resumed later if needed.
</p>
<h3>rl.resume()<span><a class="mark" href="#readline_rl_resume" id="readline_rl_resume">#</a></span></h3>
<p>Resumes the readline <code>input</code> stream.
</p>
<h3>rl.close()<span><a class="mark" href="#readline_rl_close" id="readline_rl_close">#</a></span></h3>
<p>Closes the <code>Interface</code> instance, relinquishing control on the <code>input</code> and
<code>output</code> streams. The "close" event will also be emitted.
</p>
<h3>rl.write(data, [key])<span><a class="mark" href="#readline_rl_write_data_key" id="readline_rl_write_data_key">#</a></span></h3>
<p>Writes <code>data</code> to <code>output</code> stream. <code>key</code> is an object literal to represent a key
sequence; available if the terminal is a TTY.
</p>
<p>This will also resume the <code>input</code> stream if it has been paused.
</p>
<p>Example:
</p>
<pre><code>rl.write('Delete me!');
// Simulate ctrl+u to delete the line written previously
rl.write(null, {ctrl: true, name: 'u'});</code></pre>
<h2>Events<span><a class="mark" href="#readline_events" id="readline_events">#</a></span></h2>
<h3>Event: 'line'<span><a class="mark" href="#readline_event_line" id="readline_event_line">#</a></span></h3>
<p><code>function (line) {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream receives a <code>\n</code>, usually received when the
user hits enter, or return. This is a good hook to listen for user input.
</p>
<p>Example of listening for <code>line</code>:
</p>
<pre><code>rl.on('line', function (cmd) {
console.log('You just typed: '+cmd);
});</code></pre>
<h3>Event: 'pause'<span><a class="mark" href="#readline_event_pause" id="readline_event_pause">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream is paused.
</p>
<p>Also emitted whenever the <code>input</code> stream is not paused and receives the
<code>SIGCONT</code> event. (See events <code>SIGTSTP</code> and <code>SIGCONT</code>)
</p>
<p>Example of listening for <code>pause</code>:
</p>
<pre><code>rl.on('pause', function() {
console.log('Readline paused.');
});</code></pre>
<h3>Event: 'resume'<span><a class="mark" href="#readline_event_resume" id="readline_event_resume">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream is resumed.
</p>
<p>Example of listening for <code>resume</code>:
</p>
<pre><code>rl.on('resume', function() {
console.log('Readline resumed.');
});</code></pre>
<h3>Event: 'close'<span><a class="mark" href="#readline_event_close" id="readline_event_close">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted when <code>close()</code> is called.
</p>
<p>Also emitted when the <code>input</code> stream receives its "end" event. The <code>Interface</code>
instance should be considered "finished" once this is emitted. For example, when
the <code>input</code> stream receives <code>^D</code>, respectively known as <code>EOT</code>.
</p>
<p>This event is also called if there is no <code>SIGINT</code> event listener present when
the <code>input</code> stream receives a <code>^C</code>, respectively known as <code>SIGINT</code>.
</p>
<h3>Event: 'SIGINT'<span><a class="mark" href="#readline_event_sigint" id="readline_event_sigint">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream receives a <code>^C</code>, respectively known as
<code>SIGINT</code>. If there is no <code>SIGINT</code> event listener present when the <code>input</code>
stream receives a <code>SIGINT</code>, <code>pause</code> will be triggered.
</p>
<p>Example of listening for <code>SIGINT</code>:
</p>
<pre><code>rl.on('SIGINT', function() {
rl.question('Are you sure you want to exit?', function(answer) {
if (answer.match(/^y(es)?$/i)) rl.pause();
});
});</code></pre>
<h3>Event: 'SIGTSTP'<span><a class="mark" href="#readline_event_sigtstp" id="readline_event_sigtstp">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p><strong>This does not work on Windows.</strong>
</p>
<p>Emitted whenever the <code>input</code> stream receives a <code>^Z</code>, respectively known as
<code>SIGTSTP</code>. If there is no <code>SIGTSTP</code> event listener present when the <code>input</code>
stream receives a <code>SIGTSTP</code>, the program will be sent to the background.
</p>
<p>When the program is resumed with <code>fg</code>, the <code>pause</code> and <code>SIGCONT</code> events will be
emitted. You can use either to resume the stream.
</p>
<p>The <code>pause</code> and <code>SIGCONT</code> events will not be triggered if the stream was paused
before the program was sent to the background.
</p>
<p>Example of listening for <code>SIGTSTP</code>:
</p>
<pre><code>rl.on('SIGTSTP', function() {
// This will override SIGTSTP and prevent the program from going to the
// background.
console.log('Caught SIGTSTP.');
});</code></pre>
<h3>Event: 'SIGCONT'<span><a class="mark" href="#readline_event_sigcont" id="readline_event_sigcont">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p><strong>This does not work on Windows.</strong>
</p>
<p>Emitted whenever the <code>input</code> stream is sent to the background with <code>^Z</code>,
respectively known as <code>SIGTSTP</code>, and then continued with <code>fg(1)</code>. This event
only emits if the stream was not paused before sending the program to the
background.
</p>
<p>Example of listening for <code>SIGCONT</code>:
</p>
<pre><code>rl.on('SIGCONT', function() {
// `prompt` will automatically resume the stream
rl.prompt();
});</code></pre>
<h2>Example: Tiny CLI<span><a class="mark" href="#readline_example_tiny_cli" id="readline_example_tiny_cli">#</a></span></h2>
<p>Here's an example of how to use all these together to craft a tiny command
line interface:
</p>
<pre><code>var readline = require('readline'),
rl = readline.createInterface(process.stdin, process.stdout);
rl.setPrompt('OHAI> ');
rl.prompt();
rl.on('line', function(line) {
switch(line.trim()) {
case 'hello':
console.log('world!');
break;
default:
console.log('Say what? I might have heard `' + line.trim() + '`');
break;
}
rl.prompt();
}).on('close', function() {
console.log('Have a great day!');
process.exit(0);
});</code></pre>
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