November 2013
Intermediate to advanced
148 pages
3h 12m
English
Content preview from Node.js the Right Way
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Capturing Data from an EventEmitter
EventEmitter is a very important class in Node.[11] It provides a channel for events to be dispatched and listeners notified. Many objects you’ll encounter in Node inherit from EventEmitter, like the Streams we saw in the last section.
Now let’s modify our previous program to capture the child process’s output by listening for events on the stream. Open an editor to the watcher-spawn.js file from the previous section, then find the call to fs.watch(). Replace it with this:
| file-system/watcher-spawn-parse.js | |
| | fs.watch(filename, function() { |
| | let |
| | ls = spawn('ls', ['-lh', filename]), |
| | output = ''; |
| | ls.stdout.on('data', function(chunk){ |
| | output += chunk.toString(); |
| | }); |
| | |
| | ls.on('close', ... |
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