@rinq/websocket/core/utf8/encode.js

Rinq in the browser.

module.exports = function utf8Encode (string) {
  var bytes // an array of UTF-8 bytes built from the supplied string
  var charCode // holds the current character code
  var encoded // a view into the result buffer
  var i // used for iteration

  bytes = []

  for (i = 0; i < string.length; ++i) {
    charCode = string.charCodeAt(i)

    if (charCode < 0x80) {
      bytes.push(charCode)
    } else if (charCode < 0x800) {
      bytes.push(0xc0 | charCode >> 6)
      bytes.push(0x80 | charCode & 0x3f)
    } else if (charCode < 0xd800) {
      bytes.push(0xe0 | charCode >> 12)
      bytes.push(0x80 | (charCode >> 6) & 0x3f)
      bytes.push(0x80 | charCode & 0x3f)
    } else {
      charCode = (charCode & 0x3ff) << 10
      charCode |= string.charCodeAt(++i) & 0x3ff
      charCode += 0x10000

      bytes.push(0xf0 | charCode >> 18)
      bytes.push(0x80 | (charCode >> 12) & 0x3f)
      bytes.push(0x80 | (charCode >> 6) & 0x3f)
      bytes.push(0x80 | charCode & 0x3f)
    }
  }

  encoded = new Uint8Array(bytes.length)
  encoded.set(bytes)

  return encoded.buffer
}