mirror of
https://github.com/denoland/deno.git
synced 2024-11-23 15:16:54 -05:00
159 lines
3 KiB
Markdown
159 lines
3 KiB
Markdown
# std/io
|
|
|
|
## Bufio
|
|
|
|
**Uses:**
|
|
|
|
### readLines
|
|
|
|
Read reader[like file], line by line:
|
|
|
|
```ts title="readLines"
|
|
import { readLines } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
|
|
import * as path from "https://deno.land/std@$STD_VERSION/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);
|
|
}
|
|
```
|
|
|
|
**Output:**
|
|
|
|
````text
|
|
# std/io
|
|
|
|
## readLines
|
|
|
|
```ts
|
|
import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
|
|
|
|
## Rest of the file
|
|
````
|
|
|
|
### readStringDelim
|
|
|
|
Read reader`[like file]` chunk by chunk, splitting based on delimiter.
|
|
|
|
```ts title="readStringDelim"
|
|
import { readStringDelim } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
|
|
import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
|
|
|
|
const filename = path.join(Deno.cwd(), "std/io/README.md");
|
|
let fileReader = await Deno.open(filename);
|
|
|
|
for await (let line of readStringDelim(fileReader, "\n")) {
|
|
console.log(line);
|
|
}
|
|
```
|
|
|
|
**Output:**
|
|
|
|
````text
|
|
# std/io
|
|
|
|
## readLines
|
|
|
|
```ts
|
|
import * as path from "https://deno.land/std@$STD_VERSION/path/mod.ts";
|
|
|
|
## Rest of the file
|
|
````
|
|
|
|
## Reader
|
|
|
|
### StringReader
|
|
|
|
Create a `Reader` object for `string`.
|
|
|
|
```ts
|
|
import { StringReader } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
|
|
|
|
const data = new Uint8Array(6);
|
|
const r = new StringReader("abcdef");
|
|
const res0 = await r.read(data);
|
|
const res1 = await r.read(new Uint8Array(6));
|
|
|
|
// Number of bytes read
|
|
console.log(res0); // 6
|
|
console.log(res1); // null, no byte left to read. EOL
|
|
|
|
// text
|
|
|
|
console.log(new TextDecoder().decode(data)); // abcdef
|
|
```
|
|
|
|
**Output:**
|
|
|
|
```text
|
|
6
|
|
null
|
|
abcdef
|
|
```
|
|
|
|
## Writer
|
|
|
|
### StringWriter
|
|
|
|
Create a `Writer` object for `string`.
|
|
|
|
```ts
|
|
import {
|
|
copyN,
|
|
StringReader,
|
|
StringWriter,
|
|
} from "https://deno.land/std@$STD_VERSION/io/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 Deno.copy(r, w); // copy all
|
|
console.log(w.toString()); // base0123456789
|
|
```
|
|
|
|
**Output:**
|
|
|
|
```text
|
|
base0123
|
|
base0123456789
|
|
```
|
|
|
|
## Streams
|
|
|
|
### fromStreamReader
|
|
|
|
Creates a `Reader` from a `ReadableStreamDefaultReader`.
|
|
|
|
```ts
|
|
import { fromStreamReader } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
|
|
const res = await fetch("https://deno.land");
|
|
const file = await Deno.open("./deno.land.html", { create: true, write: true });
|
|
|
|
const reader = fromStreamReader(res.body!.getReader());
|
|
await Deno.copy(reader, file);
|
|
file.close();
|
|
```
|
|
|
|
### fromStreamWriter
|
|
|
|
Creates a `Writer` from a `WritableStreamDefaultWriter`.
|
|
|
|
```ts
|
|
import { fromStreamWriter } from "https://deno.land/std@$STD_VERSION/io/mod.ts";
|
|
const file = await Deno.open("./deno.land.html", { read: true });
|
|
|
|
const writableStream = new WritableStream({
|
|
write(chunk): void {
|
|
console.log(chunk);
|
|
},
|
|
});
|
|
const writer = fromStreamWriter(writableStream.getWriter());
|
|
await Deno.copy(file, writer);
|
|
file.close();
|
|
```
|