How to fix RangeError: Value out of range. ASCII encoding only supports values 0-127 in Node.js

// Wrong - throws RangeError with non-ASCII characters
const str = 'Hello, Café';
const buf = Buffer.from(str, 'ascii'); // RangeError!

// Correct - use UTF-8 encoding
const str = 'Hello, Café';
const buf = Buffer.from(str, 'utf8');
console.log(buf); // <Buffer 48 65 6c 6c 6f 2c 20 43 61 66 c3 a9>
console.log(buf.toString('utf8')); // "Hello, Café"

function isAsciiOnly(str) {
  return /^[\x00-\x7F]*$/.test(str);
}

const str = 'Hello, Café';
if (isAsciiOnly(str)) {
  const buf = Buffer.from(str, 'ascii');
  console.log(buf);
} else {
  console.warn('String contains non-ASCII characters, cannot use ASCII encoding');
  // Use UTF-8 instead
  const buf = Buffer.from(str, 'utf8');
  console.log(buf);
}

const fs = require('fs');

// Wrong - assumes data is ASCII
fs.readFile('data.txt', 'ascii', (err, data) => {
  if (err) throw err;
  console.log(data); // Will fail with non-ASCII content
});

// Correct - use UTF-8
fs.readFile('data.txt', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data); // Works with any Unicode content
});

// Or without encoding (returns Buffer)
fs.readFile('data.txt', (err, buffer) => {
  if (err) throw err;
  const text = buffer.toString('utf8');
  console.log(text);
});

// Identify character codes in your string
const str = 'Hello, Café';
for (let i = 0; i < str.length; i++) {
  console.log(`${str[i]}: ${str.charCodeAt(i)}`);
}
// Output shows 'é' has code 233, which is > 127 (outside ASCII range)

// Check if all characters are ASCII (0-127)
const allAscii = [...str].every(ch => ch.charCodeAt(0) <= 127);
console.log(allAscii); // false - contains non-ASCII

// Use appropriate encoding
if (allAscii) {
  const buf = Buffer.from(str, 'ascii');
} else {
  const buf = Buffer.from(str, 'utf8');
}

# Find all references to ASCII encoding
grep -r ""ascii"" src/
grep -r "'ascii'" src/
grep -r "ascii" package-lock.json

// Before
Buffer.from(data, 'ascii')
buf.toString('ascii')
fs.readFile(path, 'ascii', callback)

// After
Buffer.from(data, 'utf8')
buf.toString('utf8')
fs.readFile(path, 'utf8', callback)