What is the format of the switch statement? How to use switch statement-JS Tutorial-php.cn

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What is the format of the switch statement? How to use switch statement

Nov 03, 2018 pm 01:52 PM

In js, the switch statement is also a commonly used statement. The switch statement will be used to compare an expression with multiple values. But for many novices, they don’t know what the switch statement format is? How to use switch statement? Let’s summarize it below.

Switch statement format syntax:

switch(表达式)
{
    case 取值1:
        语块1;break;
}

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In the above code, we use the case statement to mark a position. The background will output the result according to the program switch condition until it jumps to the first matching result. Then the code program will be automatically executed, including other statements, and execution will not stop until the break function is encountered. [Recommended study: JavaScript Online Manual]

Of course, the default here is optional. When other case statements are not satisfied, the default statement will be executed. The code is as follows:

<!DOCTYPE html> 
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
    <script type="text/javascript">
        var now = new Date();    //获取当天系统日期
        var day = now.getDay();   //获取当天是星期几
        var week;
        switch(day)
        {
            case 1:
                week = "星期一"; break;
            case 2:
                week = "星期二"; break;
            case 3:
                week = "星期三"; break;
            case 4:
                week = "星期四"; break;
            case 5:
                week = "星期五"; break;
            case 6:
                week = "星期六"; break;
            default:
                week = "星期日";
        }
        document.write("今天是"+week);    //输出今天是星期几
    </script>
</head>
<body>
</body>
</html>

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The display effect is as follows:

What is the format of the switch statement? How to use switch statement

Analysis:

The use of other js loop statements was also introduced earlier, however In actual development, we have to decide whether to use if statements or switch according to the actual situation. We choose not to use if statements because they are often used, but switch is not often used, let alone because switch is more efficient.

Whether it is an if statement or other statements, as long as we grasp the core point, we try to use if for relatively few judgments. For many judgment statements, we still have to use switch statements.

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