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@remy
Last active August 29, 2015 14:23
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Is this okay? The peek will just act as a benign through stream letting us see the first item. Would this add much overhead to the time do you think?
var peek = module.exports = function (fn) {
var peeked = false;
return through(function write(data) {
this.emit('data', data);
if (peeked) {
return;
}
peeked = true;
var stream = this;
var cont = function (end) {
if (end === true) {
stream.end();
} else {
stream.resume();
}
};
this.pause();
if (fn.length > 1) {
fn(data, cont);
} else {
cont(fn(data));
}
});
};
var array = new Pump(10);
array.pipe(peek(function (data) {
console.log('first item is', data); // 1
}));
array.pipe(slice(5)).on('data', collect(result)).on('end', function () {
t.equal(5, result.length);
t.end();
}));
@remy
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remy commented Jun 25, 2015

Oh, the usage handles both sync and async usage. If the peek handler only receives data, then it's sync. But it can be async with:

peek(array, function (data, done) {
  // do something async with data
  done();  // continue stream, or `done(true)` to end the stream
});

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