Which UI do you use?

Custom UI

Pre built UI

Handle Event Hook

This function is called for various user actions. It can be used for logging, analytics or any side effect purposes (these are essentially fire and forget events).

ReactJS

// this goes in the auth route config of your frontend app (once the pre built UI script has been loaded)

(window as any).supertokensUIThirdParty.init({
    onHandleEvent: (context) => {
        if (context.action === "SUCCESS") {
            if (context.createdNewSession) {
                let user = context.user;
                if (context.isNewRecipeUser && context.user.loginMethods.length === 1) {
                    // sign up success
                } else {
                    // sign in success
                }
            } else {
                // this is during linking a social account to an existing account
            }
        }
    }
})

Angular

import ThirdParty from "supertokens-auth-react/recipe/thirdparty";

ThirdParty.init({
    onHandleEvent: (context) => {
        if (context.action === "SUCCESS") {
            if (context.createdNewSession) {
                let user = context.user;
                if (context.isNewRecipeUser && context.user.loginMethods.length === 1) {
                    // sign up success
                } else {
                    // sign in success
                }
            } else {
                // this is during linking a social account to an existing account
            }
        }
    }
})

Vue

// this goes in the auth route config of your frontend app (once the pre built UI script has been loaded)

(window as any).supertokensUIThirdParty.init({
    onHandleEvent: (context) => {
        if (context.action === "SUCCESS") {
            if (context.createdNewSession) {
                let user = context.user;
                if (context.isNewRecipeUser && context.user.loginMethods.length === 1) {
                    // sign up success
                } else {
                    // sign in success
                }
            } else {
                // this is during linking a social account to an existing account
            }
        }
    }
})

info

Also checkout the session recipe handle event hook.