## Initialize Checkout

This method initializes Checkout.

This method returns a `Checkout` instance.

**Syntax:** `stripe.initCheckout(...)`

- `options` (object)
  Checkout initialization options.

  - `clientSecret` (Promise<string> | string) **required**
    The Checkout Session [client secret](/api/checkout/sessions/object.md#checkout_session_object-client_secret) or a promise that resolves to the client secret.

  - `elementsOptions` (object)
    A set of options to configure Elements created with Checkout.

    - `appearance` (object)
      Match the design of your site with the [appearance option](/elements/appearance-api.md).
The layout of each Element stays consistent, but you can modify colors, fonts, borders, padding, and more.

    - `loader` ('auto' | 'always' | 'never')
      Display skeleton loader UI while waiting for Elements to fully load after they're mounted.
Default is `'auto'` (Stripe determines whether or not to show a loader UI).

    - `fonts` (array)
      An array of custom fonts that elements created from the `Elements` object can use. You can specify fonts as [CssFontSource](#css_font_source_object) or [CustomFontSource](#custom_font_source_object) objects.

    - `savedPaymentMethod` (object)
      Options to configure what Elements displays when used to [Save payment details during payment](/payments/checkout/save-during-payment.md).

      - `enableRedisplay` ('auto' | 'never')
        Toggle if Elements redisplays Customer saved Payment Methods. Default is `'auto'`. Prior to Clover, this defaulted to `'never'`.

      - `enableSave` ('auto' | 'never')
        Toggle if the Payment Element collects consent to save a Customer's Payment Methods. Default is `'auto'`. Prior to Clover, this defaulted to `'never'`.

    - `syncAddressCheckbox` ('billing' | 'shipping' | 'none')
      Used with the [Address Element](/elements/address-element.md).

The `syncAddressCheckbox` parameter configures which Address Element to show the checkbox.

The checkbox allows the customer the option to sync billing and shipping addresses when both Billing and Shipping Address Elements are used in a single Elements instance.

  - `adaptivePricing` (object)
    Options for [Adaptive Pricing](/payments/currencies/localize-prices/adaptive-pricing.md?payment-ui=embedded-components).

    - `allowed` (boolean)
      Whether Adaptive Pricing can be used with this integration. Default is `false`.
[Additional setup](/payments/currencies/localize-prices/adaptive-pricing.md?payment-ui=embedded-components) is required before you can use Adaptive Pricing with embedded components.

  - `defaultValues` (object)
    If customer details are already known, this option may be passed to prefill the Checkout Session and related elements.

    - `billingAddress` (object)
      The Customer's billing address.

      - `name` (optional string)
        Full name.

      - `address` (optional object)
        Address.

        - `country` (string) **required**
          Two-letter country code ([ISO 3166-1 alpha-2](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2)).

        - `line1` (optional string)
          Address line 1 (e.g., street, PO Box, or company name).

        - `line2` (optional string)
          Address line 2 (e.g., apartment, suite, unit, or building).

        - `city` (optional string)
          City, district, suburb, town, or village.

        - `postal_code` (optional string)
          ZIP or postal code.

        - `state` (optional string)
          State, county, province, or region.

    - `shippingAddress` (object)
      The Customer's shipping address.

      - `name` (optional string)
        Full name.

      - `address` (optional object)
        Address.

        - `country` (string) **required**
          Two-letter country code ([ISO 3166-1 alpha-2](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2)).

        - `line1` (string) **required**
          Address line 1 (e.g., street, PO Box, or company name).

        - `line2` (optional string)
          Address line 2 (e.g., apartment, suite, unit, or building).

        - `city` (optional string)
          City, district, suburb, town, or village.

        - `postal_code` (optional string)
          ZIP or postal code.

        - `state` (optional string)
          State, county, province, or region.

    - `email` (string)
      The Customer's email address.

    - `phoneNumber` (string)
      The Customer's phone number.

### Initialize Checkout

```js
const clientSecret = createCheckoutSession();
const checkout = stripe.initCheckout({
  clientSecret,
});
```

```es_next
const clientSecret = await createCheckoutSession();
const checkout = stripe.initCheckout({
  clientSecret,
});
```