49 lines
1.1 KiB
TypeScript
49 lines
1.1 KiB
TypeScript
|
type ReadTextFileOptions = {
|
||
|
|
encoding?: string;
|
||
|
|
fallbackEncoding?: string;
|
||
|
|
};
|
||
|
|
|
||
|
|
export async function readTextFile(
|
||
|
|
file: File,
|
||
|
|
options: ReadTextFileOptions = {},
|
||
|
|
): Promise<string> {
|
||
|
|
const buf = await file.arrayBuffer();
|
||
|
|
const bytes = new Uint8Array(buf);
|
||
|
|
|
||
|
|
if (options.encoding) {
|
||
|
|
return new TextDecoder(options.encoding).decode(bytes);
|
||
|
|
}
|
||
|
|
|
||
|
|
let encoding: string = "utf-8";
|
||
|
|
let offset = 0;
|
||
|
|
|
||
|
|
if (bytes.length >= 2 && bytes[0] === 0xff && bytes[1] === 0xfe) {
|
||
|
|
encoding = "utf-16le";
|
||
|
|
offset = 2;
|
||
|
|
} else if (bytes.length >= 2 && bytes[0] === 0xfe && bytes[1] === 0xff) {
|
||
|
|
encoding = "utf-16be";
|
||
|
|
offset = 2;
|
||
|
|
} else if (
|
||
|
|
bytes.length >= 3 &&
|
||
|
|
bytes[0] === 0xef &&
|
||
|
|
bytes[1] === 0xbb &&
|
||
|
|
bytes[2] === 0xbf
|
||
|
|
) {
|
||
|
|
encoding = "utf-8";
|
||
|
|
offset = 3;
|
||
|
|
}
|
||
|
|
|
||
|
|
const content = bytes.slice(offset);
|
||
|
|
if (offset === 0 && options.fallbackEncoding) {
|
||
|
|
let utf8: string;
|
||
|
|
try {
|
||
|
|
utf8 = new TextDecoder("utf-8", { fatal: true }).decode(content);
|
||
|
|
} catch {
|
||
|
|
return new TextDecoder(options.fallbackEncoding).decode(content);
|
||
|
|
}
|
||
|
|
return utf8;
|
||
|
|
}
|
||
|
|
|
||
|
|
return new TextDecoder(encoding).decode(content);
|
||
|
|
}
|