Switch语句用于JavaScript中的多种情况

我需要在JavaScript开关语句的多个情况下，类似于:

switch (varName)
{
   case "afshin", "saeed", "larry":
       alert('Hey');
       break;

   default:
       alert('Default case');
       break;
}

我该怎么做呢?如果在JavaScript中没有办法做这样的事情，我想知道一个也遵循DRY概念的替代解决方案。

当前回答

你可以使用'in'操作符… 它依赖于对象/散列调用，所以它的速度和JavaScript一样快。

// Assuming you have defined functions f(), g(a) and h(a,b)
// somewhere in your code,
// you can define them inside the object, but...
// the code becomes hard to read. I prefer it this way.

o = { f1:f, f2:g, f3:h };

// If you use "STATIC" code can do:
o['f3']( p1, p2 )

// If your code is someway "DYNAMIC", to prevent false invocations
// m brings the function/method to be invoked (f1, f2, f3)
// and you can rely on arguments[] to solve any parameter problems.
if ( m in o ) o[m]()

2014-09-06 12:51:28

其他回答

这在常规JavaScript中工作:

function theTest(val) {
  var answer = "";
  switch( val ) {
    case 1: case 2: case 3:
      answer = "Low";
      break;
    case 4: case 5: case 6:
      answer = "Mid";
      break;
    case 7: case 8: case 9:
      answer = "High";
      break;
    default:
      answer = "Massive or Tiny?";
  }
  return answer;
}

theTest(9);

2016-01-17 02:15:47

一些有趣的方法。对我来说，最好的解决方法是使用。find。

通过在find函数中使用合适的名称，可以指示多个情况是什么。

switch (varName)
{
   case ["afshin", "saeed", "larry"].find(firstName => firstName === varName):
       alert('Hey');
       break;

   default:
       alert('Default case');
       break;
}

其他答案更适合给定的例子，但如果你有多种情况，对我来说，这是最好的方法。

2021-06-25 10:30:23

更干净的处理方法

if (["triangle", "circle", "rectangle"].indexOf(base.type) > -1)
{
    //Do something
}else if (["areaMap", "irregular", "oval"].indexOf(base.type) > -1)
{
    //Do another thing
}

您可以为具有相同结果的多个值执行此操作

2021-09-07 13:17:32

你可以这样做:

alert([
  "afshin", 
  "saeed", 
  "larry",
  "sasha",
  "boby",
  "jhon",
  "anna",
  // ...
].includes(varName)? 'Hey' : 'Default case')

或者只是一行代码:

alert(["afshin", "saeed", "larry",...].includes(varName)? 'Hey' : 'Default case')

这比埃里克的回答有所改善

2019-05-06 00:33:41

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Example1</title>
    <link rel="stylesheet" href="css/style.css" >
    <script src="js/jquery-1.11.3.min.js" type="text/javascript"></script>
    <script>
        function display_case(){
            var num =   document.getElementById('number').value;

                switch(num){

                    case (num = "1"):
                    document.getElementById("result").innerHTML = "You select day Sunday";
                    break;

                    case (num = "2"):
                    document.getElementById("result").innerHTML = "You select day  Monday";
                    break;

                    case (num = "3"):
                    document.getElementById("result").innerHTML = "You select day  Tuesday";
                    break;

                    case (num = "4"):
                    document.getElementById("result").innerHTML = "You select day  Wednesday";
                    break;

                    case (num = "5"):
                    document.getElementById("result").innerHTML = "You select day  Thusday";
                    break;

                    case (num = "6"):
                    document.getElementById("result").innerHTML = "You select day  Friday";
                    break;

                    case (num = "7"):
                    document.getElementById("result").innerHTML = "You select day  Saturday";
                    break;

                    default:
                    document.getElementById("result").innerHTML = "You select day  Invalid Weekday";
                    break
                }

        }
    </script>
</head>
<body>
    <center>
        <div id="error"></div>
        <center>
            <h2> Switch Case Example </h2>
            <p>Enter a Number Between 1 to 7</p>
            <input type="text" id="number" />
            <button onclick="display_case();">Check</button><br />
            <div id="result"><b></b></div>
        </center>
    </center>
</body>

2015-10-05 09:07:09

Switch语句用于JavaScript中的多种情况

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