client.js

// A reference to Stripe.js initialized with a fake API key.
//Sign in to see examples pre-filled with your key.
var stripe = Stripe("pk_test_TYooMQauvdEDq54NiTphI7jx");

// The items the customer wants to buy
var purchase = {
    items: [{ id: "xl-tshirt" }, { id: "xll-tshirt" }]

};

// Disable the button until we have Stripe set up on the page
document.querySelector("button").disabled = true;
fetch("/create-payment-intent", {
    method: "POST",
    headers: {
        "Content-Type": "application/json",
        'X-CSRF-TOKEN': document.head.querySelector("[name~=csrf-token][content]").content
    },
    body: JSON.stringify(purchase)
})
    .then(function(result) {
        return result.json();
    })
    .then(function(data) {
        var elements = stripe.elements();

        var style = {
            base: {
                color: "#32325d",
                fontFamily: 'Arial, sans-serif',
                fontSmoothing: "antialiased",
                fontSize: "16px",
                "::placeholder": {
                    color: "#32325d"
                }
            },
            invalid: {
                fontFamily: 'Arial, sans-serif',
                color: "#fa755a",
                iconColor: "#fa755a"
            }
        };

        var card = elements.create("card", { style: style });
        // Stripe injects an iframe into the DOM
        card.mount("#card-element");

        card.on("change", function (event) {
            // Disable the Pay button if there are no card details in the Element
            document.querySelector("button").disabled = event.empty;
            document.querySelector("#card-errors").textContent = event.error ? event.error.message : "";
        });

        var form = document.getElementById("payment-form");
        form.addEventListener("submit", function(event) {
            event.preventDefault();
            // Complete payment when the submit button is clicked
            payWithCard(stripe, card, data.clientSecret);
        });
    });

// Calls stripe.confirmCardPayment
// If the card requires authentication Stripe shows a pop-up modal to
// prompt the user to enter authentication details without leaving your page.
var payWithCard = function(stripe, card, clientSecret) {
    loading(true);
    stripe
        .confirmCardPayment(clientSecret, {
            payment_method: {
                card: card
            }
        })
        .then(function(result) {
            if (result.error) {
                // Show error to your customer
                showError(result.error.message);
            } else {
                // The payment succeeded!
                var email = document.getElementById("email").value;
                orderComplete(result.paymentIntent.id);
                fetch("/payment-success", {
                    method: "POST",
                    headers: {
                        "Content-Type": "application/json",
                        'X-CSRF-TOKEN': document.head.querySelector("[name~=csrf-token][content]").content
                    },
                    body: email
                });
            }
        });
};

/* ------- UI helpers ------- */

// Shows a success message when the payment is complete
var orderComplete = function(paymentIntentId) {
    loading(false);
    document
        .querySelector(".result-message a")
        .setAttribute(
            "href",
            "https://dashboard.stripe.com/test/payments/" + paymentIntentId
        );
    document.querySelector(".result-message").classList.remove("hidden");
    document.querySelector("button").disabled = true;
};

// Show the customer the error from Stripe if their card fails to charge
var showError = function(errorMsgText) {
    loading(false);
    var errorMsg = document.querySelector("#card-errors");
    errorMsg.textContent = errorMsgText;
    setTimeout(function() {
        errorMsg.textContent = "";
    }, 4000);
};

// Show a spinner on payment submission
var loading = function(isLoading) {
    if (isLoading) {
        // Disable the button and show a spinner
        document.querySelector("button").disabled = true;
        document.querySelector("#spinner").classList.remove("hidden");
        document.querySelector("#button-text").classList.add("hidden");
    } else {
        document.querySelector("button").disabled = false;
        document.querySelector("#spinner").classList.add("hidden");
        document.querySelector("#button-text").classList.remove("hidden");
    }
};