Gulp – Handling Errors With Streams

Gulp, Gulp – Handling Errors with Streams

What if the file was named incorrectly? What happens?

Change the string index.html to OMG_WRONG_FILE.html and rerun the script.

/streams.js 
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var fs = require("fs");
var stream = fs.createReadStream(__dirname + "/contents/OMG_WRONG_FILE.html");

stream.on("data", function(chunk) {
  // just output chunk to terminal
  console.log(chunk.toString());
});

stream.on("end", function() {
  console.log("END");
});

Running the script this time results in: 

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$ node streams.js

events.js:72
        throw er; // Unhandled 'error' event

Error: ENOENT, open '~/YOUR_DIRECTORY/OMG_WRONG_FILE.html'

If we read the error message carefully, then we can see that there is an error event we can listen to. So lets listen for that event.

/streams.js 
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...
stream.on("error", function(er) {
  console.log("error", er);
});

Now we rerun the script and see: 

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$ node streams.js

error { [Error: ENOENT, open '/Users/bunlong/js/gulp/contents/OMG_WRONG_FILE.html']
  errno: -2,
  code: 'ENOENT',
  path: '~/YOUR_DIRECTORY/contents/OMG_WRONG_FILE.html' }

And that is it for now. We will come back and use some of what we learned later.