Simple Promise script that checks for Network Ready and a secondary 'readyState' (which may be set 'true' post-login or other similar situation). This is ideally used in PWA or other web applications that are offline-enabled but need to wait for network readiness before performing a one-way action (eg. game action, etc)

wait_for_Ready_to_Send.js

// Made by Chaitanya Dhareshwar for internal use. You may use this freely in your project

window.readyToSend = false; // this is made true when the socket.connect is triggered - change it to fit your usecase. 

window.waitForRTS = async function waitForRTS(maxWaitms = 10000) {
        console.log("wait for RTS", maxWaitms);
        
        // some 'service' replace this with your connection confirmation/readyState 
        if (!socket.connected) socket.connect(); // in my case, readyToSend changes on socket connection
        
        return await new Promise(function(resolve, reject) {
            let T1 = setTimeout(() => {
                clearInterval(T0);
                clearTimeout(T1);
                console.log("RTS failed");
                return reject();
            }, maxWaitms);

            let T0 = setInterval(() => {
                if (navigator.onLine && readyToSend) {
                    clearInterval(T0);
                    clearTimeout(T1);
                    console.log("RTS success");
                    return resolve();
                }
            }, 50);
        });
    };