Transform stream that lets you peek the first line before deciding how to parse it
npm install peek-streamTransform stream that lets you peek the first line before deciding how to parse it
``
npm install peek-stream
!dat
` js
var peek = require('peek-stream')
var ldjson = require('ldjson-stream')
var csv = require('csv-parser')
var isCSV = function(data) {
return data.toString().indexOf(',') > -1
}
var isJSON = function(data) {
try {
JSON.parse(data)
return true
} catch (err) {
return false
}
}
// call parser to create a new parser
var parser = function() {
return peek(function(data, swap) {
// maybe it is JSON?
if (isJSON(data)) return swap(null, ldjson())
// maybe it is CSV?
if (isCSV(data)) return swap(null, csv())
// we do not know - bail
swap(new Error('No parser available'))
})
}
`
The above parser will be able to parse both line delimited JSON and CSV
` js
var parse = parser()
parse.write('{"hello":"world"}\n{"hello":"another"}\n')
parse.on('data', function(data) {
console.log(data) // prints {hello:'world'} and {hello:'another'}
})
`
Or
` js
var parse = parser()
parse.write('test,header\nvalue-1,value-2\n')
parse.on('data', function(data) {
console.log(data) // prints {test:'value-1', header:'value-2'}
})
`
Per default data is the first line (or the first 65535 bytes if no newline is found).
To change the max buffer pass an options map to the constructor
` js`
var parse = peek({
maxBuffer: 10000
}, function(data, swap) {
...
})
If you want to emit an error if no newline is found set strict: true` as well.
MIT