snipt

Ctrl+h for KB shortcuts

JavaScript

Stream de lectura y escritura (Node.js)

var fs = require('fs');
var readableStream = fs.ReadStream('file_input.txt');
var writableStream = fs.WriteStream('file_output.txt');

readableStream.setEncoding('utf8');
readableStream.on('data', function(data){
    writableStream.write(data);
});

readableStream.on('close', function() {
    writableStream.end();
});


// También podemos hacerlo con el método pipe(), que se encarga de gestionar 
// los eventos de lectura y escritura
var fs = require('fs');
var readableStream = fs.ReadStream('file_input.txt');
var writableStream = fs.WriteStream('file_output.txt');

readableStream.pipe(writableStream);

Description

Stream para leer el contenido de un archivo y escribirlo en otro. Muy eficiente en archivos grandes, ya que no espera a acabar de leer el input. A la vez que se produce la lectura, se va ejecutando la escritura.
https://snipt.net/embed/0fe473d63360893093d2e93683d8a5db/
/raw/0fe473d63360893093d2e93683d8a5db/
0fe473d63360893093d2e93683d8a5db
js
JavaScript
22
2019-07-23T13:45:01
True
False
False
/api/public/snipt/114699/
stream-de-lectura-y-escritura-nodejs
<table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><a href="#L-1"> 1</a> <a href="#L-2"> 2</a> <a href="#L-3"> 3</a> <a href="#L-4"> 4</a> <a href="#L-5"> 5</a> <a href="#L-6"> 6</a> <a href="#L-7"> 7</a> <a href="#L-8"> 8</a> <a href="#L-9"> 9</a> <a href="#L-10">10</a> <a href="#L-11">11</a> <a href="#L-12">12</a> <a href="#L-13">13</a> <a href="#L-14">14</a> <a href="#L-15">15</a> <a href="#L-16">16</a> <a href="#L-17">17</a> <a href="#L-18">18</a> <a href="#L-19">19</a> <a href="#L-20">20</a> <a href="#L-21">21</a></pre></div></td><td class="code"><div class="highlight"><pre><span></span><span id="L-1"><a name="L-1"></a><span class="kd">var</span> <span class="nx">fs</span> <span class="o">=</span> <span class="nx">require</span><span class="p">(</span><span class="s1">&#39;fs&#39;</span><span class="p">);</span> </span><span id="L-2"><a name="L-2"></a><span class="kd">var</span> <span class="nx">readableStream</span> <span class="o">=</span> <span class="nx">fs</span><span class="p">.</span><span class="nx">ReadStream</span><span class="p">(</span><span class="s1">&#39;file_input.txt&#39;</span><span class="p">);</span> </span><span id="L-3"><a name="L-3"></a><span class="kd">var</span> <span class="nx">writableStream</span> <span class="o">=</span> <span class="nx">fs</span><span class="p">.</span><span class="nx">WriteStream</span><span class="p">(</span><span class="s1">&#39;file_output.txt&#39;</span><span class="p">);</span> </span><span id="L-4"><a name="L-4"></a> </span><span id="L-5"><a name="L-5"></a><span class="nx">readableStream</span><span class="p">.</span><span class="nx">setEncoding</span><span class="p">(</span><span class="s1">&#39;utf8&#39;</span><span class="p">);</span> </span><span id="L-6"><a name="L-6"></a><span class="nx">readableStream</span><span class="p">.</span><span class="nx">on</span><span class="p">(</span><span class="s1">&#39;data&#39;</span><span class="p">,</span> <span class="kd">function</span><span class="p">(</span><span class="nx">data</span><span class="p">){</span> </span><span id="L-7"><a name="L-7"></a> <span class="nx">writableStream</span><span class="p">.</span><span class="nx">write</span><span class="p">(</span><span class="nx">data</span><span class="p">);</span> </span><span id="L-8"><a name="L-8"></a><span class="p">});</span> </span><span id="L-9"><a name="L-9"></a> </span><span id="L-10"><a name="L-10"></a><span class="nx">readableStream</span><span class="p">.</span><span class="nx">on</span><span class="p">(</span><span class="s1">&#39;close&#39;</span><span class="p">,</span> <span class="kd">function</span><span class="p">()</span> <span class="p">{</span> </span><span id="L-11"><a name="L-11"></a> <span class="nx">writableStream</span><span class="p">.</span><span class="nx">end</span><span class="p">();</span> </span><span id="L-12"><a name="L-12"></a><span class="p">});</span> </span><span id="L-13"><a name="L-13"></a> </span><span id="L-14"><a name="L-14"></a> </span><span id="L-15"><a name="L-15"></a><span class="c1">// También podemos hacerlo con el método pipe(), que se encarga de gestionar </span> </span><span id="L-16"><a name="L-16"></a><span class="c1">// los eventos de lectura y escritura</span> </span><span id="L-17"><a name="L-17"></a><span class="kd">var</span> <span class="nx">fs</span> <span class="o">=</span> <span class="nx">require</span><span class="p">(</span><span class="s1">&#39;fs&#39;</span><span class="p">);</span> </span><span id="L-18"><a name="L-18"></a><span class="kd">var</span> <span class="nx">readableStream</span> <span class="o">=</span> <span class="nx">fs</span><span class="p">.</span><span class="nx">ReadStream</span><span class="p">(</span><span class="s1">&#39;file_input.txt&#39;</span><span class="p">);</span> </span><span id="L-19"><a name="L-19"></a><span class="kd">var</span> <span class="nx">writableStream</span> <span class="o">=</span> <span class="nx">fs</span><span class="p">.</span><span class="nx">WriteStream</span><span class="p">(</span><span class="s1">&#39;file_output.txt&#39;</span><span class="p">);</span> </span><span id="L-20"><a name="L-20"></a> </span><span id="L-21"><a name="L-21"></a><span class="nx">readableStream</span><span class="p">.</span><span class="nx">pipe</span><span class="p">(</span><span class="nx">writableStream</span><span class="p">);</span> </span></pre></div> </td></tr></table>
node.js, stream