默认情况下，PayPal会呈现所有符合条件的按钮。但是，某些集成允许覆盖此设置。PayPal调用这些资金来源。此示例演示了如何自定义可用的资金来源。

// Loop over each funding source/payment method
paypal.getFundingSources().forEach(function (fundingSource) {
  // Initialize the buttons
  var button = paypal.Buttons({
    fundingSource: fundingSource,
  })
  // Check if the button is eligible
  if (button.isEligible()) {
    // Render the standalone button for that funding source
    button.render('#paypal-button-container')
  }
})