# ThreeDS JavaScript Library
source: https://developer.mastercard.com/mastercard-gateway/documentation/api-reference/js-libraries/three-ds/index.md

## ThreeDS SDK overview {#threeds-sdk-overview}

The threeDS.js is a JavaScript based client-side SDK for EMV 3DS authentication flows for online payments.
Note: Supported only in API version 54 and later.

## URL {#url}

`https://{{host}}}}/static/threeDS/1.3.0/three-ds.min.js`

## Functions {#functions}

[configure()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/threeds/version/100/function/configure.html?locale=en_US)
Configuration method for initializing the API.

[isConfigured()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/threeds/version/100/function/isConfigured.html?locale=en_US)
Convenience method to check if the API has been configured successfully.

[onEvent()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/threeds/version/100/function/onEvent.html?locale=en_US)
Method to subscribe for event changes.

[initiateAuthentication()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/threeds/version/100/function/initiateAuthentication.html?locale=en_US)
Initiate 3DS Authentication for the arguments passed.

[authenticatePayer()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/threeds/version/100/function/authenticatePayer.html?locale=en_US)
Authentication method for authenticating payer using 3DS that was initiated using initiateAuthentication call.

[getLastCorrelationId()](https://network.gateway.mastercard.com/api/documentation/apiDocumentation/threeds/version/100/function/getLastCorrelationId.html?locale=en_US)
Get the last correlation id that was used for making the REST API call.