# Checkout JavaScript Library
source: https://developer.mastercard.com/mastercard-gateway/documentation/api-reference/js-libraries/checkout/index.md
The checkout.min.js JavaScript library allows simple payment integrations for merchant sites.
## URL {#url}
`https://{{host}}/static/checkout/checkout.min.js`
## Functions {#functions}
[configure()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/function/configure.html?locale=en_US)
Prepare the library before payment.
[showEmbeddedPage()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/function/showEmbeddedPage.html?locale=en_US)
Show a hosted payment form embedded into the merchant site.
[showPaymentPage()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/function/showPaymentPage.html?locale=en_US)
Redirect to a hosted payment page to complete payment.
[saveFormFields()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/function/saveFormFields.html?locale=en_US)
A default implementation of a beforeRedirect callback.
[restoreFormFields()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/function/restoreFormFields.html?locale=en_US)
A default implementation of an afterRedirect callback.
## Callbacks {#callbacks}
[error](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/callback/error.html?locale=en_US)
Invoked when error occurs during initiation of payment.
[complete](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/callback/complete.html?locale=en_US)
Invoked when payment has been completed.
[cancel](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/callback/cancel.html?locale=en_US)
When the payer cancels the payment interaction. Note: Cancel callback can only be used with payment page, it will not work with embedded page.
[timeout](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/callback/timeout.html?locale=en_US)
Invoked when the payment is not completed within the duration available to the payer to make the payment.
[beforeRedirect](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/callback/beforeRedirect.html?locale=en_US)
Invoked before browser is redirected away from page.
[afterRedirect](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/checkout/version/100/callback/afterRedirect.html?locale=en_US)
Invoked when browser returns to page after redirect.
## Example {#example}
```HTML
...