j/source.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <title>JS Bin</title>
</head>

<body>
    <textarea id='miniForth'>

  </textarea>

    <div id='asm'>

    </div>
</body>

<script>
    XXXPARSERXXX


    var W;
    var H;
    var M = document.getElementById('miniForth');
    var A = document.getElementById('asm')
    A.style.backgroundColor = '#F1F1F1';

    M.value = String.raw`XXXREADMEXXX`

    window.setInterval(() => {
        // window size
        W = window.innerWidth;
        H = window.innerHeight;
        M.style.height = H / 2 + 'px';
        M.style.width = W + 'px';
        A.style.height = H / 2 + 'px';
        A.style.width = W + 'px';

        // parse result
        var i = M.value
        var o;
        try {
            o = peg$parse(i)
        } catch (err) {
            o = err
        }
        //   console.log(o)

        A.innerText = o;

    }, 1000)


</script>

</html>