[USER SUBMITTED GUIDE] How to access the new MAL API using OAuth 2.0

function onComplete()
{
    console.log(this.responseText);
}

const request = new XMLHttpRequest();
request.addEventListener("load", onComplete);
request.open("GET", "https://api.myanimelist.net/v2/users/@me");
request.setRequestHeader("Authorization", "Bearer YOUR_ACCESS_TOKEN");
request.send();  // Use "request.send(JSON.stringify({ ... }))" when you need
                 // to include parameters inside the body of the HTTP request.

function onComplete()
{
    console.log(this.responseText);
}

const request = new XMLHttpRequest();
request.addEventListener("load", onComplete);
request.open("GET", "https://cors-anywhere.herokuapp.com/api.myanimelist.net:443/v2/users/@me");
request.setRequestHeader("Authorization", "Bearer YOUR_ACCESS_TOKEN");
request.send();

function onComplete()
{
    console.log(this.responseText);
}

const encodeParameters = p => Object.entries(p).map(kv => kv.map(encodeURIComponent).join("=")).join("&");

const request = new XMLHttpRequest();
request.addEventListener("load", onComplete);
request.open("POST", "https://cors-anywhere.herokuapp.com/myanimelist.net:443/v1/oauth2/token");
request.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
request.send(encodeParameters({
    client_id: "CLIENT ID",
    client_secret: "CLIENT SECRET",
    code: "AUTHORISATION CODE",
    code_verifier: "CODE VERIFIER",
    grant_type: "authorization_code"
}));

function onComplete() //Don't change anything on this line!
{
    console.log(this.responseText); //Don't change anything on this line!
} //Don't change anything on this line!

const encodeParameters = p => Object.entries(p).map(kv => kv.map(encodeURIComponent).join("=")).join("&"); //Don't change anything on this line!

const request = new XMLHttpRequest(); //Don't change anything on this line!
request.addEventListener("load", onComplete); //Don't change anything on this line!
request.open("POST", "https://cors-anywhere.herokuapp.com/myanimelist.net:443/v1/oauth2/token"); //Don't change anything on this line!
request.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); //Don't change anything on this line!
request.send(encodeParameters({
    client_id: "CLIENT_ID",
    client_secret: "CLIENT_SECRET",
    code: "AUTHORIZATION_CODE", //This needs to be replaced.You will get this on step 2
    code_verifier: "CODE_VERIFIER", //Paste the Generated Code Verifier numbers in the place of "CODE VERIFIER"
    grant_type: "authorization_code" //Don't change anything on this line!
})); //Don't change anything on this line!

function generateCodeVerifier() {
    var code_verifier = generateRandomString(128);
    document.getElementById("code_verifier").value = code_verifier;
}

function generateRandomString(length) {
    var text = "";
    var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~";
    for (var i = 0; i < length; i++) {
        text += possible.charAt(Math.floor(Math.random() * possible.length));
    }
    return text;
}