js数据类型及转换

野性酷女 2022-07-13 23:20 339阅读 0赞

<!DOCTYPE html>
    <html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
        <script>
    //--------------------js中的数据类型------------------------------
    //      var str = "abc"; //字符串
    //      var num = 18;   //数字
    //      var bool = true; //bool类型
    //      var bbb = null; //空字符串
    //      var aaa;
    
    
    //-------------------js中的数据转换--------------------------------
            //转换成字符串
            //    var bool = true;
            //    var num = 111;
            //    var aaa;
            //    var bbb = null;
            //
            //    console.log(typeof(bool+""));
            //    console.log(typeof(num+""));
            //    console.log(typeof(aaa+""));
            //    console.log((aaa+""));
            //    console.log(typeof(bbb+""));
            //
            //    console.log(typeof(String(bool)));
            //    console.log(typeof(num.toString()));
    
    
            //转换成数字
            //    var str = "11";
            //    var bool = true;
            //    console.log(typeof (str-0));
            //    console.log(typeof (bool-0));
            //    console.log(typeof (str*1));
            //    console.log(typeof (bool*1));
            //    console.log(typeof (str/1));
            //    console.log(typeof (bool/1));
            //    console.log(typeof typeof (bool/1));  //数据类型是用string定义的
            //
            //    console.log(typeof Number(str));
            //    console.log(typeof Number(bool));
            //
            //
            //    var str2 = "12.34abc";
            //    var str3 = "12.34";
            //    console.log(parseInt(str2));
            //    console.log(parseFloat(str2));
            //    console.log(Number(str3));
    
    
            //布尔类型转换
            var date = new Date();    //
    
            console.log(Boolean(0));
            console.log(Boolean(""));
            console.log(Boolean(null));
            console.log(!!1);
            console.log(!!"abc");
            console.log(!!date);
    
    
        </script>
    </body>
    </html>