Discord DM

// VARIABLES
var channelid = '_________________';
var authorization = '_____________________________________';

// FUNCTIONS
Object.size = function(obj) {
    var size = 0, key;
    for (key in obj) {
        if (obj.hasOwnProperty(key)) size++;
    }
    return size;
};

function sleep(ms) {
	return new Promise(resolve => setTimeout(resolve, ms));
}

function deleteOneMessage(id) {
	var xhr = new XMLHttpRequest();
	xhr.open("DELETE", "https://discordapp.com/api/v6/channels/"+channelid+"/messages/"+id, true);
	xhr.setRequestHeader("authorization", authorization);
	xhr.onreadystatechange = function() {
		if (xhr.readyState == 4) {
			console.log("deleted: "+id+" "+xhr.status);
		}
	}
	xhr.send();
}

async function deleteAllMessages(ids) {
	for (var i=0; i<ids.length; i++) {
		deleteOneMessage(ids[i]);
		await sleep(200);
	}
	getId();
}

function getId() {
	var xhr = new XMLHttpRequest();
	xhr.open("GET", "https://discordapp.com/api/v6/channels/"+channelid+"/messages?limit=100", true);
	xhr.setRequestHeader("authorization", authorization);
	xhr.onreadystatechange = function() {
		if (xhr.readyState == 4 && (xhr.status == 200 || xhr.status == 0)) {
			var obj = JSON.parse(xhr.responseText);
			var size = Object.size(obj);

			var ids = new Array();
			for (var i=0; i<size; i++) {
				ids[i] = obj[i].id;
			}

			deleteAllMessages(ids);
		}
	}
	xhr.send();
}

getId();