A small promise-based wrapper for through2
npm install through2-promise``
npm install --save through2-promise
Some examples:
`javascript
var through2 = require("through2-promise");
fs.createReadStream('ex.txt')
.pipe(through2(function (chunk) {
for (var i = 0; i < chunk.length; i++) {
if (chunk[i] == 97)
chunk[i] = 122; // swap 'a' for 'z'
this.push(chunk);
}
}))
.pipe(fs.createWriteStream('out.txt'))
.on('finish', function () {
doSomethingSpecial()
});
`
Or object streams:
`javascript
var all = []
fs.createReadStream('data.csv')
.pipe(csv2())
.pipe(through2.obj(function (chunk) {
var data = {
name : chunk[0],
address : chunk[3],
phone : chunk[10]
};
this.push(data);
}))
.on('data', function (data) {
all.push(data)
})
.on('end', function () {
doSomethingSpecial(all)
});
`
. You can throw within your function to
automatically reject the promise and error-out the stream. options is the optional object that gets passed into through2.this is the through2 stream, so you can do this.push() just like in through2. If you return a Promise, and
the Promise resolves to a value, this value will be written to the stream (just like passing a value to the
callback in through2).flushFunction() is a function that runs after the source stream has been consumed. It has access to this.push()`,