JS Bin // source https://jsbin.com/mebinir

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

function runCommands(commands, obj) {
  const newObj = Object.assign({}, obj)
  commands.forEach(function(com) {
    switch(com.type) {
        case 'REPLACE_NAME': {
          newObj.name = com.value
          break;
        }
          
        default: {
          break;
        }
    }
  })
  return newObj
}

const o1 = {
  name: 'Frodo'
}

const o2 = runCommands(instructions, o1)

console.log(o1)
console.log(o2)
</script>

const o1 = {
  name: 'Frodo'
}

const o2 = runCommands(instructions, o1)

console.log(o1)
console.log(o2)
</script></body>
</html>