proxy.js

function proxy(context, target, assert) {
  let queue = []

  function send(methodName, ...methodArguments) {
    const object = context[target]
    if (object && eval(assert)) {
      object[methodName](...methodArguments)
    }
    else {
      queue.push({methodName, methodArguments})
    }
  }
  send.register = function (...methodNames) {
    for (let i = 0; i < methodNames.length; i++) {
      this[methodNames[i]] = this.bind(null, methodNames[i])
    }
  }


  function runQueue() {
    const object = context[target]
    for (let i = 0, invoke ; i < queue.length ; i++) {
      invoke = queue[i]
      object[invoke.methodName](...invoke.methodArguments)
    }
    queue = []
  }

  (function loop() {
    if (context[target] && eval(assert)) {
      runQueue()
    }
    else {
      setTimeout(loop, 500)
    }
  })()

  return send
}