Method setEncoding

lib/api/readable.js:327–362

* @param {BufferEncoding} encoding * @returns {this}

(encoding)

   * @returns {this}
   */
  setEncoding (encoding) {
    if (Buffer.isEncoding(encoding)) {
      // Preserve raw Buffer chunks for the consume path (body.text(),
      // body.json(), etc.) before super.setEncoding() replaces them
      // with decoded strings. Without this, the consume path would
      // lose access to the original bytes — some of which may be held
      // by the decoder for incomplete multi-byte sequences, and the
      // rest converted to strings that can't be safely concatenated
      // byte-wise.
      const state = this._readableState
      const buffer = state.buffer
      if (buffer && state.length > 0) {
        const bufferIndex = state.bufferIndex ?? 0
        const preserved = []
        const source = typeof buffer.slice === 'function'
          ? buffer.slice(bufferIndex)
          : buffer
        for (const data of source) {
          if (Buffer.isBuffer(data)) {
            preserved.push(data)
          }
        }
        if (preserved.length > 0) {
          this[kPreservedBuffer] = (this[kPreservedBuffer] || []).concat(preserved)
        }
      }

      // Delegate to Node.js Readable.setEncoding() which initializes a
      // StringDecoder and re-encodes already-buffered chunks. This properly
      // handles multi-byte sequences split at chunk boundaries for the
      // for-await / on('data') paths. Without this, Node.js uses
      // buf.toString(encoding) on each chunk, producing U+FFFD for split chars.
      super.setEncoding(encoding)
    }
    return this
  }
}

/**