javascript - 如何知道 PayPal Smart Payment Button 是否完成渲染

Question

我正在尝试 add the PayPal Smart Payment button to my website .用于呈现按钮的 HTML 容器通过 AJAX 请求接收，其中 paypal.Buttons.render() 方法称为 AJAX 请求的 onsuccess。现在一切正常，除了按钮需要一些时间在网站上呈现并激活。我想提示我的用户按钮正在呈现或加载，因此当 AJAX 请求返回并且没有显示按钮时，他们不会蒙在鼓里。有没有办法知道按钮何时完全呈现？

$.ajax({
  url: example/foler,
  data: data,
  success: success(data)
});

function success(data) {
  // data = <div id='paypal-button-container'></div>
  paypal.Buttons().render('#paypal-button-container');

  // Display "Button Loading..."
  // Find out if button has completely rendered, then turn off "button loading..."
}

Answer 1

您可以使用 .then(callback)，因为 render() 返回一个 Promise。

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promises

A Promise is an object representing the eventual completion or failure of an asynchronous operation. Since most people are consumers of already-created promises, this guide will explain consumption of returned promises before explaining how to create them.

Essentially, a promise is a returned object to which you attach callbacks, instead of passing callbacks into a function.

$.ajax({
  url: example/foler,
  data: data,
  success: success(data)
});

function success(data) {
  // data = <div id='paypal-button-container'></div>
  // Display "Button Loading..."
  paypal.Buttons().render('#paypal-button-container').then(function() { 
    // Button has completely rendered, then turn off "button loading..."
  });

}