function reverse(str) {
  debugger ← insert 'debugger'
  return str.split('').reduce((reversed, character)=>character + reversed,'')
}
reverse('apple')

node inspect xxx.js

// type 'continue'
debug> continue

// or type just 'c'
debug> c

// type 'repl'
debug> repl

> str
'apple'

> str.split('').reduce((reversed, character)=>character + reversed,'')
'elppa'