golang: NewReader vs NewBufferString

NewReader

func bytes.NewReader(b []byte) *bytes.Reader

bytes.NewReader on pkg.go.dev

NewReader returns a new Reader reading from b.

NewBufferString

func bytes.NewBufferString(s string) *bytes.Buffer

bytes.NewBufferString on pkg.go.dev

NewBufferString creates and initializes a new Buffer using string s as its initial contents. It is intended to prepare a buffer to read an existing string.

Difference

// A Reader implements the io.Reader, io.ReaderAt, io.WriterTo, io.Seeker,
// io.ByteScanner, and io.RuneScanner interfaces by reading from
// a byte slice.
// Unlike a Buffer, a Reader is read-only and supports seeking.
// The zero value for Reader operates like a Reader of an empty slice.

The bufferString creates a mutable buffer.