（前端）2.js变量作用域样例

<!DOCTYPE html>
<html>
<head>
    <title>变量作用域样例</title>
    <script src="/lib/jquery/dist/jquery.js"></script>
</head>
<body>
    <h1>变量作用域样例</h1>
    <script>
    </script>
    <script>
        var a = 1;//当前作用域的变量a
        console.log("3: a的值是：" + a); //1
        function test() {
            var a = 3;//当前作用域是test函数体内，变量a重定义了，函数体里的a都是它
            console.log("1:a的值是：", a); //3
            a = 4;
            console.log("2:a的值是：", a); //4
            return a;
        }
        var b = test();//4
        console.log("b的值是：" + b);
        a = 10;//修改了全局的变量a
        var c = test();//4
        console.log("c的值是：" + c);
    </script>
    <script>
        console.log("4: a的值是：" + a);//搜索同一级<script>标签里定义的变量a的值
    </script>
</body>
</html>