[Python知识库] 【四十二】Python全栈之路--JS

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[Python知识库]【四十二】Python全栈之路--JS

文章目录

1. js对象

1.1 object对象

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>object对象</title>
</head>
<body>
    <script>

        // 1.定义对象方法一
        var obj = new Object();
        console.log(obj , typeof(obj))
        obj.name = "孙坚";
        obj.age = 18;
        obj.weight = "200斤";
        obj.eat = function(){
            alert("我会吃竹子");
        }
        console.log(obj.name)
        // obj.eat();

        //2.定义对象方法二
        /* 对象中的成员不要使用单引号,在特殊场景中,比如json格式字符串的转换中会报错; */
        var obj = {
            name:"张三",
            "age" : 20,
            sex   : "男性",
            drink : function(something){
                console.log("我会喝牛栏山",something);
            }
        }
        //调用方式一
        console.log(obj.sex)
        obj.drink("老白干")
        //调用方式二
        console.log(obj["age"])
        obj["drink"](1)
        // 注意点
        var str = "name"
        console.log(obj.str , "<==========================>") //error
        console.log(obj.name)
        console.log(obj[str]) // obj["name"]
        
        // eval 可以把字符串当成代码执行
        eval("console.log(333)")

        //3.定义对象方法三
        /* 类比python中定义类的写法 , this等价于self */
        function Person(name,age,sex){
            this.name = name;
            this.age = age;
            this.sex = sex;
            this.func = function(){
                console.log("我是func");
                return this.sex;
            }
        }

        var obj1 = new Person("刘一风",30,"男性");
        var obj2 = new Person("张三风",90,"女性");
        console.log(obj1.name);
        var res = obj1.func();
        console.log(res);
        console.log(obj2.name)
        var res = obj2.func();
        console.log(res);

        //4.遍历对象 
        for(var i in obj1){
            console.log(i)
        }

        //5. with(对象) 语法可以直接获取对象成员的值
        with(obj1){
            console.log(name);
            console.log(sex);
            console.log(age);
            res = func();
            console.log(res);
        }
        console.log("<===================================>")
        //将4和5结合,遍历对象中的数据;
        for(var i in obj1){
            //console.log(i , typeof(i)) // name age sex func  ... string
            with(obj1){
                console.log(eval(i))
            }
        }


    </script>
    
</body>
</html>

1.2 json对象

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>json对象</title>
</head>
<body>
    <script>
        var data = {
            'name':"文东",
            age:20,
            "sleep":function(){
                alert("文东一天睡23小时,还有一个小时上厕所.");
            }
        }
        // js对象 => json格式的字符串
        var res = JSON.stringify(data);
        console.log(res , typeof(res)); // {"name":"文东","age":20} 

        // json格式的字符串 => js对象
        res = '{"name":"东东","age":30}';  // success
        // res = "{'name':90,'age':40}"; error 引号必须是双引号
        var res2 = JSON.parse(res);
        console.log(res2,typeof(res2));
        


    </script>

</body>
</html>

2. js字符串函数

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>字符串对象的相关方法</title>
</head>
<body>
    <script>
        var string = "to be or not to be";
        //获取字符串长度 length	
        var res = string.length
        var res = string[-1]
        console.log(res)

        //1.清除两侧的空白 trim [ python的strip ]
        var res = string.trim()
        console.log(string)
        console.log(res)

        //2.获取首次出现的位置 indexOf   [ python的find ]
         /*找不到返回-1*/
        var string = "to be or not to be";
        var res = string.indexOf("z")
        console.log(res)

        //3/最后一次出现的位置 lastIndexOf 
        /*找不到返回-1*/
        var res = string.lastIndexOf("zzz")
        console.log(res);

        //4.连接字符串	concat	 [ python的 os.path.join  + ]
        var res = string.concat("d:\\","python32\\","day42");
        console.log(res);

        //5.截取字符串 slice
        /* string.slice(开始值,结束值) 字符串的切片  留头舍尾  [支持逆向下标]*/
        var string = "11122233e or not to be";
        var res = string.slice(1,7);
        var res = string.slice(-5,-1);      // to b
        // var res = string.slice(-5,-10); //截取不到返回空
        console.log(res,"<==1==>")

        //6.截取字符串 substr
        /* string.substr(开始值,截取几个) */
        var string = "11122233e or not to be";
        var res = string.substr(3,4)
        console.log(res,"<==2==>")

        //7.拆分字符串 split  [ python的 split ]
        var string = "11122233e or not to be";
        var res = string.split(" ")
        console.log(res,"<==3==>")

        //8.大小写 toUpperCase toLowerCase
        var string = "11122233e Or noT tO be";
        res = string.toUpperCase();
        res = string.toLowerCase();
        console.log(res,"<==4==>")

        //9.search 匹配第一次找到的索引位置,找不到返回-1
        var string = "aaabbb oldaoy ccc"
        var res = string.search(/oldboy/)
        console.log(res,"<==5==>")

        //10.match 返回匹配的数据
        /* /正则表达式/修饰符 g:全局匹配 i:不区分大小写 m:多行匹配  */
        var string = "我的电话是 : 13838384388 你的电话是: 13854381438"
        var res = string.match(/\d{11}/);  // 匹配一个
        var res = string.match(/\d{11}/g); // 匹配多个,(需要修饰符加上g)
        console.log(res)
        console.log(res[0])
        console.log(res[1])

        //11.字符串替换 replace
        /* replace默认只替换一次 */
        var string = "to be or not to be";
        var res = string.replace("to","two")
        console.log(res,"<==6==>")       

        // 方法一:
        function myreplace(string,a,b){
            /*
                找最后一个to,如果找不到返回-1
                如果能找到就不停的进行替换,直到-1为止,循环终止;
            */
            while(string.lastIndexOf(a) != -1){
                console.log(1)
                string = string.replace(a,b);
            }
            return string;
        }     
        var string = "to be or not to be";   
        var res = myreplace(string,"to","two")
        console.log(res) // two be or not two be

        // 方法二
        var string = "to be or not to be";
        var res = string.replace(/to/g,"two");
        console.log(res)
    </script>
</body>
</html>