tap-object-stream

Quickly tap into properties of streamed objects.

• Install
• Examples
  • Single return value
  • Multiple return values
  • Go deep
  • Filter objects in a stream
• License

Install

npm i tap-object-stream --save

Examples

Single return value

var tap = require('tap-object-stream')
 
// By introspection, the function parameter 
// names are mapped to object properties
tap(function(count, add) {
  return count + add, 
})
 
.on('data', function(obj){
  console.log(obj.count) // 3
})
 
.write({ count: 1, add: 2 })

Multiple return values

// Add "done" as a parameter
tap(function(count, color, done) {
  done(3, 'blue')
})
 
.on('data', function(obj){
  console.log(obj.count, obj.color) // 3, 'blue'
})
 
.write({ count: 0, color: 'red' })

Go deep

// Properties don't have to exist beforehand
tap('files[0].data', function(name){
  return 'bob'
})
 
.on('data', function(obj){
  console.log(obj.files[0].data.name) // 'bob'
})
 
.write({ files: [{ data: {} }]})

Filter objects in a stream

var stream = tap(function(color, done) {
  done.exclude(color==='red')
})
 
// Will only output the blue and green objects
stream.on('data', console.log.bind(console))
 
stream.write({ color: 'blue' })
stream.write({ color: 'red' })
stream.write({ color: 'green' })
stream.end()

Available methods:

• done.include() or done.exclude(false)
• done.include(false) or done.exclude()

To emit an error and stop streaming, use:

• done.assert() or done.refute(false)
• done.assert(false) or done.refute()

License

MIT © Vincent Weevers