如何使用开关案例范围的JavaScript
[英]how use switch case range JavaScript
问题描述
I'm trying to using siwtch case JavaScript like this 
我正在尝试像这样使用siwtch case JavaScript
<p id="demo"></p>
<script>
var n=new Date();
var jam=n.getHours();
switch (jam) {
case (jam>='17'):
time = "sleep";
break;
case (jam<'17'):
time = "work";
break;
}
document.getElementById("demo").innerHTML = "This Time for " + time;
</script>
but this didn't appear anything 但这什么也没出现
4 个解决方案
解决方案1
2 2016-10-18 06:30:32
You are using switch()case in incorrect way. 您以错误的方式使用了switch()case 。 Because switch is used when you are trying to check states, but not ranges. 因为在尝试检查状态而不是范围时使用了switch 。 If you want to check ranges, you'd rather use if()else state like this: 如果要检查范围，则宁愿使用if()else状态，如下所示：
<p id="demo"></p>
<script>
var n=new Date();
var jam=n.getHours();
if ( parseInt(jam) >= 17){
time = "sleep";
} else if ( parseInt(jam) <17)
time = "work";
} else {
time = " play :) "
}
document.getElementById("demo").innerHTML = "This Time for " + time;
</script>
解决方案2
1 2016-10-18 06:31:23
You need to modify the switch case if you are trying to check range using switch , else you have to go for the traditional if else condition. 如果尝试使用switch来检查范围，则需要修改switch的大小写，否则必须采用传统的if else条件。 I have modified the code as per your requirement. 我已根据您的要求修改了代码。 Please check this one. 请检查这个。
<html> <body> <p id="demo"></p> <script> var n=new Date(); var jam=n.getHours(); var time = ""; switch (true) { case (jam>=17): time = "sleep"; break; case (jam<17): time = "work"; break; } document.getElementById("demo").innerHTML = "This Time for " + time; </script> </body> </html>
否则使用。
<html> <body> <p id="demo"></p> <script> var n=new Date(); var jam=n.getHours(); var time = ""; if (jam>=17){ time = "sleep"; } else if (jam<17){ time = "work"; } document.getElementById("demo").innerHTML = "This Time for " + time; </script> </body> </html>
解决方案3
0 2016-10-18 06:36:59
You may use a case and use a condition in the case statement and true in the select part. 您可以在case语句中使用case并使用条件，在select部分中使用true 。
The use a fall trough style to check smalles value first and the bigger values. 使用下降槽样式先检查较小值和较大值。 The check must use numbers, not strings as in the example. 支票必须使用数字，而不是示例中的字符串。
at least you coluld use a default branch and assign somthing default like, which works when all other condition are not met. 至少您可以使用默认分支并分配类似默认值的东西，当不满足所有其他条件时，它可以工作。
var n = new Date(), jam = n.getHours(), time = ''; switch (true) { case (jam < 9): // this leads to if (true === (jam < 9)) { ... time = "coffee"; break; case (jam < 17): time = "work"; break; case (jam < 19): time = "relaxing"; break; default: time = "sleep"; } console.log("This Time for " + time); console.log(jam);
解决方案4
0 2016-10-18 06:37:35
I have fixed your code, here is the js fiddle 我已经修复了您的代码，这是js小提琴
https://jsfiddle.net/qkpmkzoh/ https://jsfiddle.net/qkpmkzoh/
And the fixed code is this. 固定的代码是这个。
var n=new Date();
var jam=n.getHours();
var time = "";
console.log(jam);
switch (true) {
case jam>=17:
time = "sleep";
break;
case jam<17:
time = "work";
break;
}
document.getElementById("demo").innerHTML = "This Time for " + time
However I would recommend you to use if else, as it makes the code more readable 但是，我建议您使用其他方式，因为这会使代码更易读
var n=new Date();
var jam=n.getHours();
var time = "";
console.log(jam);
if (jam>=17){
time = "sleep";
}
else if(jam<17) {
time = "work";
}
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