import{Readable,Transform} from"node:stream";
import{text} from"node:stream/consumers";
import{pipeline} from"node:stream/promises";
// A Node.js-style Transform that converts data to uppercase
// and appends a newline to the end of the output.
classMyTransformextendsTransform{
constructor(){
super({ encoding:"utf8"});
}
_transform(chunk,_,cb){
this.push(chunk.toString().toUpperCase());
cb();
}
_flush(cb){
this.push("\n");
cb();
}
}
exportdefault{
asyncfetch(){
constchunks= [
"hello ",
"from ",
"the ",
"wonderful ",
"world ",
"of ",
"node.js ",
"streams!",
];
functionnextChunk(readable){
readable.push(chunks.shift());
if (chunks.length===0)readable.push(null);
elsequeueMicrotask(()=>nextChunk(readable));
}
// A Node.js-style Readable that emits chunks from the
// array...
constreadable=newReadable({
encoding:"utf8",
read(){
nextChunk(readable);
},
});
consttransform=newMyTransform();
awaitpipeline(readable,transform);
returnnewResponse(awaittext(transform));
},
};