Introduction to JavaScript data types-JS Tutorial-php.cn

Introduction to JavaScript data types

巴扎黑

Release： 2017-08-04 10:59:56

Original

1026 people have browsed it

This article introduces you to the usage examples of the six data types of JavaScript. For knowledge about JavaScript, you can search for relevant content on PHP中文网.

Related recommendations: http://www.php.cn/code/793.html

1 Numeric type

Numeric type includes: integer type, float, NaN.

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           //现在我们想让一个东西的长度变成原来的10倍
           var length = "300m";
           /*
           一个字符串，是不能转换成有意义的数值的，只能转换成NaN
           一个含纯数字的字符串，可以转成有意义的数值，大家可以修改length为纯数字的字符串，输出查看结果
           */
           length = length*10;
           document.write(length);
        </script>
    </head>
    <body>
    </body>
</html>

Copy after login

2.Character type

A string enclosed by single or double quotes

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script type="text/javascript">
            var name = "小明";
            //加号为字符串连接符，我们之后会介绍
            var str = "我的名字叫做&#39;" +name+"&#39;"
            document.write(str)
        </script>
    </head>
    <body>
    </body>
</html>

Copy after login

3.Boolean type

Boolean type is also Called logical type. There are only two values: true (true), false (false).

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script type="text/javascript">
           var x = 10;
           var y = 110;
           //x>y比较出来的结果是布尔值
           if(x>y){
               document.write(x+"比"+y+"大些");
           }else{
               document.write(y+"比"+x+"大些");
           }
        </script>
    </head>
    <body>
    </body>
</html>

Copy after login

4. Escape character

The meaning character is backslash (\).

Commonly used escape characters include: \', \”, \\, \r, \n, etc.

That is, when the browser encounters a backslash (\) , the following character will be treated specially and treated as a normal character. The so-called "normal" characters are a, b, c, &, etc. 5. Null value

##. #When an object does not exist, the empty type will be returned. The value of the empty type is only null.

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script type="text/javascript">
            var name = "小明";
            //加号为字符串连接符，我们之后会介绍
            var str = "我的名字叫做\"" +name+"\""
            document.write(str)
        </script>
    </head>
    <body>
    </body>
</html>

Copy after login

6. Undefined value

When a variable is defined but not assigned a value, it will be returned. Returns an undefined type, and the value of an undefined type has only one undefined

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script type="text/javascript">
            var x = null;
            document.write(x);
        </script>
    </head>
    <body>
    </body>
</html>

Copy after login

The above is the detailed content of Introduction to JavaScript data types. For more information, please follow other related articles on the PHP Chinese website!