# Link Authentication Element

Use the Link Authentication Element to integrate Link.

[Link](https://stripe.com/payments/link) saves and autofills customer payment and shipping information. Customers can use different funding sources to pay with Link, including credit cards, debit cards, and US bank accounts. Learn more at [link.com](https://www.link.com).

Use the [Link Authentication Element](https://docs.stripe.com/js/element/link_authentication_element) to create a single email input field for both email collection and Link authentication.

| 选项                          | 描述                                                                                                                                                                     |
| --------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Theme**                   | Use the dropdown to choose a theme or customize the theme with the [Elements Appearance API](https://docs.stripe.com/elements/appearance-api.md).                      |
| **Desktop and mobile size** | Use the dropdown to set the max pixel width of the parent element that the Address Element is mounted to. You can set it to 750px (Desktop) or 320px (Mobile).         |
| **Customer location**       | Use the dropdown to choose a location for accepting complete addresses. Changing the location localizes the UI language and displays locally relevant payment methods. |
| **Layout**                  | Use the dropdown to display the element using tabs (displayed horizontally) or accordion (displayed vertically) layouts.                                               |

## Start with examples 

To see the Link Authentication Element in action, start with one of these examples:

[快速开始](https://docs.stripe.com/payments/link/add-link-elements-integration.md): Code and instructions for accepting a payment and using the Link Authentication Element to integrate Link.

[在 GitHub 上克隆一个示例应用程序](https://github.com/stripe-samples/accept-a-payment)

## Before you begin

Before you start, you need to [register your domain](https://docs.stripe.com/payments/payment-methods/pmd-registration.md).

## Create the Link Authentication Element 

The following code [creates](https://docs.stripe.com/js/elements_object/create_link_authentication_element) an instance of the Link Authentication Element and [mounts](https://docs.stripe.com/js/element/mount) it to the DOM:

#### HTML + JS

```javascript
// Enable the skeleton loader UI for the optimal loading experience.
const loader = 'auto';

// Create an elements group from the Stripe instance passing in the clientSecret and enabling the loader UI.
const elements = stripe.elements({clientSecret, loader});

// Create an instance of the Link Authentication Element.
const linkAuthenticationElement = elements.create("linkAuthentication");

// Mount the Elements to their corresponding DOM node
linkAuthenticationElement.mount("#link-authentication-element");
paymentElement.mount("#payment-element");
```

#### React

```jsx
import {loadStripe} from "@stripe/stripe-js";
import {
  Elements,
  LinkAuthenticationElement,
  PaymentElement,
} from "@stripe/react-stripe-js";

const stripe = loadStripe('<<YOUR_PUBLISHABLE_KEY>>');

// Enable the skeleton loader UI for the optimal loading experience.
const loader = 'auto';

const CheckoutPage = ({clientSecret}) => (
  <Elements stripe={stripe} options={{clientSecret, appearance, loader}}>
    <CheckoutForm />
  </Elements>
);

export default function CheckoutForm() {
  return (
    <form>
      <h3>Contact info</h3>
      <LinkAuthenticationElement/>
      <h3>Payment</h3>
      <button type="submit">Submit</button>
    </form>
  );
}
```

## Retrieving email address 

您可以使用 `linkAuthenticationElement` 组件上的 `onChange` 属性检索电子邮件地址详细信息。每当用户更新电子邮件字段或自动填充已保存的客户电子邮件时，`onChange` 处理程序就会触发。

```javascript
linkAuthenticationElement.on('change', (event) => {
  const email = event.value.email;
});
```

## Prefill customer data  

The Link Authentication Element accepts an email address. Providing a customer’s email address starts the Link authentication flow as soon as the customer lands on the payment page using the [defaultValues](https://docs.stripe.com/js/elements_object/create_link_authentication_element#link_authentication_element_create-options-defaultValues) option:

```javascript
// Create the Link Authentication Element with the defaultValues option
const linkAuthenticationElement = elements.create("linkAuthentication", {defaultValues: {email: "foo@bar.com"}});

// Mount the Link Authentication Element to its corresponding DOM node
linkAuthenticationElement.mount("#link-authentication-element");
```

如果您想预填其他客户数据，请将 [defaultValues.billingDetails](https://docs.stripe.com/js/elements_object/create_payment_element#payment_element_create-options-defaultValues-billingDetails) 对象添加到 [Payment Element](https://docs.stripe.com/payments/payment-element.md) 中。这将预填客户的姓名、电话号码和收货地址。通过尽可能多地预填客户信息，您可以简化 Link 账户的创建和重复使用流程。

以下代码显示了一个预填了所有值的 Payment Element：

#### React

```jsx
<PaymentElement
  options={{
    defaultValues: {
      billingDetails: {
        name: 'John Doe',
        phone: '888-888-8888',
        address: {
          postal_code: '10001',
          country: 'US',
        }
      },
    },
  }}
/>;
```

#### HTML + JS

```javascript
const paymentElement = elements.create('payment', {
  defaultValues: {
    billingDetails: {
      name: 'John Doe',
      phone: '888-888-8888',
      address: {
        postal_code: '10001',
        country: 'US',
      },
    },
  },
});

// Mount the Element to its corresponding DOM node
paymentElement.mount("#payment-element");
```

## Combine Elements 

The Link Authentication Element only interacts with the Payment Element by prefilling payment information for returning Link users. However, it can still be displayed with other elements as well, like the following example with the Link Authentication Element, Address Element, and Payment Element:
![结账页面包含 Link Authentication Element、Address Element 和 Payment Element。](https://b.stripecdn.com/docs-statics-srv/assets/lae-with-ae-pe.b70e0386757f6061d9b27c7211794173.png)

Use the Link Authentication Element with other Elements to compose your checkout page

## Appearance 

You can use the [Appearance API](https://docs.stripe.com/elements/appearance-api.md) to control the style of all elements. Choose a theme or update specific details.
![付款元素结账表单的亮暗模式示例。](https://b.stripecdn.com/docs-statics-srv/assets/appearance_example.e076cc750983bf552baf26c305e7fc90.png)

Use the Appearance API to change the look and style of your Elements

In the following example, the “flat” theme overrides the default text color used for Elements:

```javascript
const stripe = Stripe('<<YOUR_PUBLISHABLE_KEY>>');

const appearance = {
  theme: 'flat'
  variables: { colorPrimaryText: '#262626' }
};
const options = { /* options */ };
const elements = stripe.elements({ clientSecret, appearance }); // In a working integration, this is a value your backend passes with details such as the amount of a payment. See full sample for details.
const paymentElement = elements.create('payment', options);
paymentElement.mount('#payment-element');
```