let successCallback = function (apps) {
    console.log("UPI supported apps", apps);
}
let failureCallback = function (err) {
    console.error("Issue in fetching UPI supported apps ", err);
}

window["UPI"].supportedApps(successCallback, failureCallback);

let config = {
        "pa": "pa", // VPA no from UPI payment acc
        "pn": "pn", // Merchant Name registered in UPI payment acc
        "me": "me", // Merchant Code from UPI payment acc
        "tid": "tid", // Unique transaction id for merchant's reference
        "tr": "tr", // Unique transaction id for merchant's reference
        "tn": "tn", // Note that will displayed in payment app during transaction
        "am": "am", // Amount 
        "mam": "mam", // its optional. Minimum amount that has to be transferred 
        "cu": "cu", // Currency of amount
        "url": "url" // URL for the order
};

or

let config = {
        "payeeVPA": "pa", // VPA no from UPI payment acc
        "payeeName": "pn", // Merchant Name registered in UPI payment acc
        "payeeMerchantCode": "me", // Merchant Code from UPI payment acc
        "transactionId": "tid", // Unique transaction id for merchant's reference
        "transactionRef": "tr", // Unique transaction id for merchant's reference
        "transactionNote": "tn", // Note that will displayed in payment app during transaction
        "amount": "am", // Amount 
        "minimumAmount": "mam", // its optional. Minimum amount that has to be transferred 
        "currency": "cu", // Currency of amount
        "transactionRefUrl": "url" // URL for the order
};
let successCallback = function (result) { 
    /* success and failure of payment will be given in this method, this is because each payment uses different name to represent the status of transaction under "Status" field.*/
    console.log("result of success interaction of payment app", result);
}
let failureCallback = function (err) {
    console.error("Issue in interaction and completion of payment with UPI", err);
}

window["UPI"].acceptPayment(config, successCallback, failureCallback);