with undefined foo test

withtest.js

var locals = {}

var err

do {
  err = undefined
  try {
    with(locals) {
      foo
      bar
      kewl
      console.log('all ok')
    }
  } catch(e) {
    err = e
    if (err.type === 'not_defined') {
      locals[err.arguments[0]] = undefined
    }
  }
} while(err && err.type === 'not_defined')

console.log('done')