使用嵌套的 switch 命令(nested switch statements)

Question

尝试使用嵌套的switch命令来针对特定字段生成正确的输出。在这个具体的示例中，房屋地下室、一楼或二楼的标题值取决于房屋的总层数。我已经尝试了两个不同的脚本，但都没有得到任何输出。

// 第一个脚本：

switch (this.getField("Floor Location").value) {

  case "-":
    event.value = "-";
    break;

  case "B":
    switch ((this.getField("Storeys").value)) {
      case "-":
        event.value = "-";
        break;
      case "One Storey":
        event.value = "11";
        break;
      case "Two Storeys":
        event.value = "17";
        break;
    }

  case 'M':
    switch (this.getField("Storeys").value) {
      case "-":
        event.value = "-";
        break;
      case "One Storey":
        event.value = "1";
        break;
      case "Two Storeys":
        event.value = "11";
        break;
    }

  case "2nd":
    switch (this.getField("Storeys").value) {
      case "-":
        event.value = "-";
        break;
      case "One Storey":
        event.value = "_";
        break;
      case "Two Storeys":
        event.value = "1";
        break;
    }
  default:
    event.value = this.getField("Floor Location").value;
    break;
}

// 没有任何输出

// 第二个脚本：

var TwoStoreys = storeys;
var floor = this.getField("Floor Location").value;
if (floor = "-");
var none = floor;
var storeys = this.getField("Storeys").value;
if (storeys = "-");
var zero = storeys;
if (storeys = "One storey");
var OneStorey = storeys;
if (storeys = "Two Storeys");
var TwoStoreys = storeys;

var floor = this.getField("Floor Location").value;
if (floor = "-");
var none = floor;

if (floor = "B");
var B = floor

if (floor = "M");
var M = floor

if (floor = "2nd");
var Second = floor;

switch (true) {
  case ((zero) && (none)):
    event.value = "-";
    break;
  case ((zero) && (B)):
    event.value = "-";
    break;
  case ((zero) && (M)):
    event.value = "-";
    break;
  case ((zero) && (Second)):
    event.value = "-";
    break;
  case ((Onestorey) && (none)):
    event.value = "-";
    break;
  case ((Onestorey) && (B)):
    event.value = "11";
    break;
  case ((Onestorey) && (M)):
    event.value = "1";
    break;
  case ((Onestorey) && (Second)):
    event.value = "-";
    break;
  case ((Twostoreys) && (none)):
    event.value = "-";
    break;
  case ((Twostoreys) && (B)):
    event.value = "17";
  case ((Twostoreys) && (M)):
    event.value = "11";
    break;
  case ((Twostoreys) && (Second)):
    event.value = "1";
    break;
}

gsm2009 · Answer

1 - 第一个脚本

缺少break语句的情况：

switch (this.getField("Floor Location").value) {

    case "-": 
        event.value = "-";
        break;

    case "B":
        (this.getField("Store").value) {
            case "-": 
                event.value = "-";
                break;
            case "One Storey":
                event.value = "11";
                break;
            case "Two Storeys":                           
                event.value = "17";
                break;
        }
        break; //ADDED
    
    case 'M':
        switch (this.getField("Storeys").value) {
            case "-": 
                event.value = "-";
                break;
            case "One Storey":
                event.value = "1";
                break;
            case "Two Storeys":
                event.value = "11";
                break;
        }
        break; //ADDED
     
    case "2nd":   
        switch (this.getField("Storeys").value) {
            case "-": 
                event.value = "-";
                break;
            case "One Storey":
                event.value = "_";
                break;
            case "Two Storeys":
                event.value = "1";
                break;
        }
        break; //ADDED

    default:
        event.value = this.getField("Floor Location").value;
        break;

2 - 第二个脚本

在第二个脚本中，使用条件判断时误用了赋值操作符“=”而非等于运算符“===”，这是主要的错误。您只需将“=”改为“===”即可解决该问题。不过，我已经为您修改了这个错误：

var floor = this.getField("Floor Location").value;
var storeys = this.getField("Storeys").value;
var zero, oneStorey, twoStoreys, none, B, M, Second;

if (storeys === "-") {
  zero = storeys;
} 
if (storeys === "One storey") {
  oneStorey = storeys;
}
if (storeys === "Two Storeys") {
  twoStoreys = storeys;
}

if (floor === "-") {
  none = floor;
}
if (floor === "B") {
  B = floor;
}
if (floor === "M") {
  M = floor;
}
if (floor === "2nd") {
  Second = floor;
}

switch (true) {
  case ((zero === storeys) && (none === floor)):
    event.value = "-";
    break;
  case ((zero === storeys) && (B === floor)):
    event.value = "-";
    break;
  case ((zero === storeys) && (M === floor)):
    event.value = "-";
    break;
  case ((zero === storeys) && (Second === floor)):
    event.value = "-";
   break;
  case ((oneStorey === storeys) && (none === floor)):
    event.value = "-";
    break;
  case ((oneStorey === storeys) && (B === floor)):
    event.value = "11";
    break;
  case ((oneStorey === storeys) && (M === floor)):
    event.value = "1";
    break;
  case ((oneStorey === storeys) && (Second === floor)):
    event.value = "-";
   break;
  case ((twoStoreys === storeys) && (none === floor)):
    event.value = "-";
    break;
  case ((twoStoreys === storeys) && (B === floor)):
    event.value = "17";
  case ((twoStoreys === storeys) && (M === floor)):
    event.value = "11";
    break;
  case ((twoStoreys === storeys) && (Second === floor)):
    // Please set the expected output for this case
    event.value = "YOUR_EXPECTED_VALUE";
    break;
}

其他建议：

1 - 将所有变量声明集中放在代码的顶部。
2 - 避免重复声明同一变量。
3 - 在进行比较时，使用“===”而非“==”，以防止意外的类型转换。
4 - 在switch语句中提供一个默认值。

gsm2009 · Answer

我建议使用一个对象来映射这些值，完全摒弃switch语句的使用：

const map = {
  B: {
    "-": "-",
    "One Storey": "11",
    "Two Storeys": "17"
  },
  "2nd": {
    "-": "-",
    "One Storey": "_",
    "Two Storeys": "1"
  }
};

let floorLocation = "B"; //this.getField("Floor Location").value;
let storeys = "Two Storeys"; //this.getField("Storeys").value;

let result = map[floorLocation]?.[storeys];
if (typeof result === "undefined") {
  result = "-";
}

console.log(result);

floorLocation = "2nd";
storeys = "One Storey";

result = map[floorLocation]?.[storeys];
if (typeof result === "undefined") {
  result = "-";
}

console.log(result);

floorLocation = "-";
storeys = "-";

result = map[floorLocation]?.[storeys];
if (typeof result === "undefined") {
  result = "-";
}

console.log(result);

注意：我使用了optional chaining，这样就不必担心楼层位置是否已定义。另外，由于默认情况下所有未定义的值都会显示为“-”，所以也可以去掉那些“-”条目。