std/io
readLines
Read reader[like file], line by line:
import { readLines } from "https://deno.land/std@0.160.0/io/mod.ts";
import * as path from "https://deno.land/std@0.160.0/path/mod.ts";
const filename = path.join(Deno.cwd(), "std/io/README.md");
let fileReader = await Deno.open(filename);
for await (let line of readLines(fileReader)) {
console.log(line);
}
readStringDelim
Read reader[like file]
chunk by chunk, splitting based on delimiter.
import { readStringDelim } from "https://deno.land/std@0.160.0/io/mod.ts";
import * as path from "https://deno.land/std@0.160.0/path/mod.ts";
const filename = path.join(Deno.cwd(), "std/io/README.md");
let fileReader = await Deno.open(filename);
for await (let line of readStringDelim(fileReader, "\n")) {
console.log(line);
}
StringReader
Create a Reader
object for string
.
import { StringReader } from "https://deno.land/std@0.160.0/io/mod.ts";
const data = new Uint8Array(6);
const r = new StringReader("abcdef");
const res0 = await r.read(data);
const res1 = await r.read(new Uint8Array(6));
// Number of bytes read
console.log(res0); // 6
console.log(res1); // null, no byte left to read. EOL
// text
console.log(new TextDecoder().decode(data)); // abcdef
Output:
6
null
abcdef
StringWriter
Create a Writer
object for string
.
import {
copyN,
StringReader,
StringWriter,
} from "https://deno.land/std@0.160.0/io/mod.ts";
import { copy } from "https://deno.land/std@0.160.0/streams/mod.ts";
const w = new StringWriter("base");
const r = new StringReader("0123456789");
await copyN(r, w, 4); // copy 4 bytes
// Number of bytes read
console.log(w.toString()); //base0123
await copy(r, w); // copy all
console.log(w.toString()); // base0123456789
Output:
base0123
base0123456789