v8.isStringOneByteRepresentation

History

v8.isStringOneByteRepresentation(content): boolean

Attributes

content:string

Returns:boolean

V8 only supports Latin-1/ISO-8859-1 and UTF16 as the underlying representation of a string. If the content uses Latin-1/ISO-8859-1 as the underlying representation, this function will return true; otherwise, it returns false.

If this method returns false, that does not mean that the string contains some characters not in Latin-1/ISO-8859-1. Sometimes a Latin-1 string may also be represented as UTF16.

import { isStringOneByteRepresentation } from 'node:v8';
import { Buffer } from 'node:buffer';

const Encoding = {
  latin1: 1,
  utf16le: 2,
};
const buffer = Buffer.alloc(100);
function writeString(input) {
  if (isStringOneByteRepresentation(input)) {
    console.log(`input: '${input}'`);
    buffer.writeUint8(Encoding.latin1);
    buffer.writeUint32LE(input.length, 1);
    buffer.write(input, 5, 'latin1');
    console.log(`decoded: '${buffer.toString('latin1', 5, 5 + input.length)}'\n`);
  } else {
    console.log(`input: '${input}'`);
    buffer.writeUint8(Encoding.utf16le);
    buffer.writeUint32LE(input.length * 2, 1);
    buffer.write(input, 5, 'utf16le');
    console.log(`decoded: '${buffer.toString('utf16le', 5, 5 + input.length * 2)}'`);
  }
}
writeString('hello');
writeString('你好');

JavaScript

const { isStringOneByteRepresentation } = require('node:v8');
const { Buffer } = require('node:buffer');

const Encoding = {
  latin1: 1,
  utf16le: 2,
};
const buffer = Buffer.alloc(100);
function writeString(input) {
  if (isStringOneByteRepresentation(input)) {
    console.log(`input: '${input}'`);
    buffer.writeUint8(Encoding.latin1);
    buffer.writeUint32LE(input.length, 1);
    buffer.write(input, 5, 'latin1');
    console.log(`decoded: '${buffer.toString('latin1', 5, 5 + input.length)}'\n`);
  } else {
    console.log(`input: '${input}'`);
    buffer.writeUint8(Encoding.utf16le);
    buffer.writeUint32LE(input.length * 2, 1);
    buffer.write(input, 5, 'utf16le');
    console.log(`decoded: '${buffer.toString('utf16le', 5, 5 + input.length * 2)}'`);
  }
}
writeString('hello');
writeString('你好');

JavaScript