JVZoo IPN verification function (ported from PHP one)

jvzoo-IPN-verification.js

/*

Hello dear developers,

I ported this function for JVZoo IPN verification from PHP one at 
(https://jvzoo.zendesk.com/hc/en-us/articles/206456857-JVZIPN-How-to-create-your-own-integrated-script) and 
wanted to share that with all fellow devs. 


REF: https://jvzoo.zendesk.com/hc/en-us/articles/206456857-JVZIPN-How-to-create-your-own-integrated-script

Kodos :)
OffS3c

*/

// the requires
var utf8 = require('utf8');
const crypto = require("crypto");

// proper sha1 generator
function sha1(data) {
    return crypto.createHash("sha1").update(data, "binary").digest("hex");
}

// Function to be exported ;) modules.export .... 
function isJvzipnVerified(callbackResponse) { 

    let secretKey = "YOUR_KEY";
    let pop = "";
    let ipnFields = [];

    for (let key in callbackResponse) {
        if (key == "cverify") {
            continue;
        } else {
            ipnFields.push(key);
        }
    }
    
    ipnFields.sort();

    for (let key in ipnFields) {
        pop += callbackResponse[ipnFields[key]] + "|";
    }

    pop += secretKey;    
    calcedVerify = sha1(utf8.encode(pop));
    calcedVerify = (calcedVerify.substr(0,8)).toUpperCase();

    return calcedVerify == callbackResponse.cverify;
}



//--------------- HOW TO USE ---------------

// printer
function __(str) {
    console.log(str);
}

// data posted by JVZoo
let x = `{
        "caffitid" : "",
        "ccustcc" : "",
        "ccustemail" : "",
        "ccustname" : "",
        "ccuststate" : "",
        "cproditem" : "",
        "cprodtitle" : "",
        "cprodtype" : "",
        "ctransaction" : "",
        "ctransaffiliate" : "",
        "ctransamount" : "",
        "ctranspaymentmethod" : "",
        "ctransreceipt" : "",
        "ctranstime" : "",
        "ctransvendor" : "",
        "cupsellreceipt" : "",
        "cvendthru" : "",
        "cverify" : ""
}
`;

// parse as JS Object
x = JSON.parse(x);

// The REAL Deal
if (isJvzipnVerified(x)) {
    __("yeah");
} else {
    __("nah");
}


// ------- Thanks ------- 

Where did you get x from, is that supposed to be the $_POST field data sent by jvzoo or what ?