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73 lines
1.7 KiB
73 lines
1.7 KiB
4 years ago
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# Split (matcher)
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[](http://travis-ci.org/dominictarr/split)
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Break up a stream and reassemble it so that each line is a chunk. matcher may be a `String`, or a `RegExp`
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Example, read every line in a file ...
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``` js
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fs.createReadStream(file)
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.pipe(split())
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.on('data', function (line) {
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//each chunk now is a separate line!
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})
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```
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`split` takes the same arguments as `string.split` except it defaults to '/\r?\n/' instead of ',', and the optional `limit` parameter is ignored.
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[String#split](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/split)
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`split` takes an optional options object on its third argument.
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``` js
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split(matcher, mapper, options)
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```
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Valid options:
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* maxLength - The maximum buffer length without seeing a newline or `matcher`,
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if a single line exceeds this, the split stream will emit an error.
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``` js
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split(JSON.parse, null, { maxLength: 2})
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```
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* trailing - By default the last buffer not delimited by a newline or `matcher` will be emitted. To prevent this set `options.trailing` to `false`.
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``` js
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split(JSON.parse, null, { trailing: false })
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```
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## keep matched splitter
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As with `String#split`, if you split by a regular expression with a matching group,
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the matches will be retained in the collection.
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```
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stdin
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.pipe(split(/(\r?\n)/))
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... //lines + separators.
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```
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# NDJ - Newline Delimited Json
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`split` accepts a function which transforms each line.
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``` js
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fs.createReadStream(file)
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.pipe(split(JSON.parse))
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.on('data', function (obj) {
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//each chunk now is a a js object
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})
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.on('error', function (err) {
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//syntax errors will land here
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//note, this ends the stream.
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})
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```
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# License
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MIT
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