Taps a nodejs stream and logs the data that's coming through.
npm install tap-stream
Given an object stream we can print out objects passing through and control the detail via the depth parameter:
objectStream().pipe(tap(0));
objectStream().pipe(tap(1));
objectStream().pipe(tap(2));
For even more control a custom log function may be supplied:
objectStream()
.pipe(tap(function customLog (data) {
var nest = data.nest;
console.log ('Bird: %s, id: %s, age: %s, layed egg: %s', nest.name, data.id, nest.age, nest.egg !== undefined);
})
);Bird: yellow rumped warbler, id: 0, age: 1, layed egg: true
Bird: yellow rumped warbler, id: 1, age: 1, layed egg: true
Intercepts the stream and logs data that is passing through.
-
optional parameter is either a
Numberor aFunction -
if no parameter is given,
depthdefaults to0andlogtoconsole.log(util.inspect(..)) -
depthcontrols thedepthwith which util.inspect is called -
logreplaces the default logging function with a custom one
Example:
var tap = require('tap-stream');
myStream
.pipe(tap(1)) // log intermediate results
.pipe(..) // continute manipulating the dataIncluded in order to give context for above examples.
function objectStream () {
var s = new Stream()
, objects = 0;
var iv = setInterval(
function () {
s.emit('data', {
id: objects
, created: new Date()
, nest: {
name: 'yellow rumped warbler'
, age: 1
, egg: { name: 'unknown' , age: 0 }
}
}
, 4
);
if (++objects === 2) {
s.emit('end');
clearInterval(iv);
}
}
, 200);
return s;
}