41.local-vars.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <pre class="rect"></pre>
    <script>
        const rect = document.querySelector(".rect");
        let a = 10;

        const f1 = function (b) {
            const f2 = function (c) {
                console.log({a, b, c});
            };
            f2(30);
            // console.log({a, b, c}); ； c is invisible
        };
        f1(20);

        const g1 = function (a) {
                const g2 = function (a) {
                    console.log("1:", a); //
                };
                g2(30);
                console.log("2:", a);
            };
            g1(20);
            console.log("3:", a);
    </script>
</body>
</html>