[jmcnulty]

Understand. Did some quick tests myself and see what you mean.

Here's a version that doesn't use "here string" and so doesn't create temporary files.

  #!/bin/bash

  shopt -s lastpipe

  string="Los Angeles, London, Belfast, New York"
  echo "${string/, /,}" | readarray -d, -t arrayA
  echo ${arrayA[0]}
  echo ${arrayA[1]}

Also, the lastpipe option runs the readarray in the context of the current process.