split a Text Stream into a Line Stream

Split (matcher)

Break up a stream and reassemble it so that each line is a chunk. matcher may be a String, or a RegExp

Example, read every line in a file ...

    .on('data', function (line) {
      //each chunk now is a seperate line! 

split takes the same arguments as string.split except it defaults to '/\r?\n/' instead of ',', and the optional limit paremeter is ignored. String#split

split takes an optional options object on it's third argument.

  split(matcher, mapper, options)

Valid options:

  • maxLength - The maximum buffer length without seeing a newline or matcher, if a single line exceeds this, the split stream will emit an error.
  split(JSON.parse, null, { maxLength: 2})
  • trailing - By default the last buffer not delimited by a newline or matcher will be emitted. To prevent this set options.trailing to false.
  split(JSON.parse, null, { trailing: false })

As with Array#split, if you split by a regular expression with a matching group, the matches will be retained in the collection.

... //lines + separators.

NDJ - Newline Delimited Json

split accepts a function which transforms each line.

  .on('data', function (obj) {
    //each chunk now is a a js object 
  .on('error', function (err) {
    //syntax errors will land here 
    //note, this ends the stream.