JavaScript

JavaScript - Async - Generation 3 - Async / Await logic

From
https://www.joshwcomeau.com/javascript/promises/

After problems with Promises were established, a version 3 technology was released and called Async / Await.

Sample code

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<html>
<head>
    <meta charset="utf-8">
    <title>JavaScript - Async - Generation 2 - Promises</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="description" content="used by atom.xls">    
</head>
<body>
    <h1>JavaScript - Async - Level 2 - Promises</h1>
    
    <script>
        // Run JavaScript after the DOM is fully loaded
        document.addEventListener('DOMContentLoaded', async function () {
            console.log('DOM fully loaded and parsed.');
            // Your script logic here
            
            console.log('Start');

            await countdown()
            
            // end of event listener
        });


        async function countdown() {
            console.log("5…");
            await wait(1000);
            console.log("4…");
            await wait(1000);
            console.log("3…");
            await wait(1000);
            console.log("2…");
            await wait(1000);
            console.log("1…");
            await wait(1000);
            console.log("Happy New Year!");
        }

        function wait(duration) {
        return new Promise((resolve) => {
            setTimeout(
            () => resolve(),
            duration
            );
        });
        }



        
    </script>

</body>

</html>

The trick about Async/Await is that they can only be called from within Async functions. So out handler was modified

document.addEventListener('DOMContentLoaded', async function () {

    console.log('DOM fully loaded and parsed.');

});