<Js>数据类型

//Number:数字
    var num = new Number(1.568);
    document.write("num = "+num+"<br>");

    var num1 = 20.1;
    document.write("num1 = "+num1+"<br>");

//清空
    num1 = null;
    document.write("num1 = "+num1+"<br>");

//无value
    var num2;
    document.write("num2 = "+num2+"<br><br>");

//String:字符
    var str = new String("ABC");
    document.write("str = "+str+"<br>");

    var str1 = 'asd';
    document.write("str1 = "+str1+"<br><br>");

//Array:数组
    var arr = new Array("a",'d',1);
    document.write("arr = "+arr+"<br>");

    var arr1 = ["a",'d',1];
    document.write("arr1 = "+arr1+"<br>");

    arr1[0] = "dd";
    arr1[1] = '12';
    document.write("arr1,arr1 = "+arr1[0]+","+arr1[1]+"<br><br>");

//Boolean:布尔
    var bool = true;
    document.write("bool = "+bool+"<br>");
    bool = false;
    document.write("bool = "+bool+"<br><br>");

//Object:类
    var obj = {
        df:"df",
        sss:'12',
        ff:[1,'3',true]
    } 
    document.write(obj["df"]+"<br>");
    document.write(obj.sss);