transform-file

transform file

Transform a file as a stream in place (with a temp file, but retaining inode info)

Usage

Take a look at the test folder for more usages, but the basic idea is you pass in a file, a transform callback and a done callback and it calls the transform callback on each chunk passing in a buffer and a boolean that's true if it's the last chunk in the file, the callback can be async or sync, by either accepting a third arg or not. Here's an example:

var transformFile = require('transform-file');

transformFile(
  __dirname + '/package.json',
  function(buffer, isLastChunk) {
    return buffer.toString().toUpperCase() + (isLastChunk ? '\n\n\n' : '');
  },
  function() {
    fs.readFile(__dirname + '/package.json', function(err, buffer) {
      console.log(buffer.toString()); // uppercase with trailing newlines
    });
  }
);

// same as above just async
transformFile(
  __dirname + '/package.json',
  function(buffer, isLastChunk, next) {
    setTimeout(function() {
      // notice we use next() and not return
      next(buffer.toString().toUpperCase() + (isLastChunk ? '\n\n\n' : ''));
    }, 10);
  },
  function() {
    fs.readFile(__dirname + '/package.json', function(err, buffer) {
      console.log(buffer.toString()); // uppercase with trailing newlines
    });
  }
);