条件运算符在 javascript 中无法按预期工作

Question

以下条件运算符未按预期工作 我已将条件包含在基于场景中。

如果没有 src 或 tar 匹配，应该是 rate=0

如果 src 存在于 arr 并且是 SGD 并且 src 存在于 arr 并且是 SGD（反之亦然），则比率为 0.4

如果 src 存在于 arr 并且是 "EUR" || "GBP" || "USD" 并且 tar 存在于 arr 并且是 "SGD"，（反之亦然），则比率为 0.3

如果arr 中存在src，arr 中存在tar，则速率应为0.5

场景：

(src==="SGD" and tar==="AUD") or (src==="AUD" && tar==="SGD")  => rate="0.4"
src === "SGD") and (tar === "EUR" or "GBP" or "USD") => rate=0.3
(src==`arr` values  and tar==`arr` values)=> rate=0.5 
(src no match arr && tar no match arr)=> rate=0

var arr =["AED","BGN","CAD","CHF","CZK","DKK","HKD","HUF","ILS","INR",
       "JPY","MXN","NOK","NZD","PLN","QAR","RON","SAR","SEK","THB","TRY","ZAR"];

I tried , but not working if src="SGD" and tar="CNY" it should rate =0
var res=
      ((src === "SGD" && tar === "AUD") || (src  === "AUD" && tar === "SGD"))?
      rate = 0.4 : 
      ((src === "SGD" && (tar === "EUR" || "GBP" || "USD")) ||
      ((src === "EUR" || "GBP" || "USD") && tar === "SGD"))?
      rate = 0.3:
      (src.indexOf(arr)!=-1 && tar.indexOf(arr)!=-1) ?
      rate = 0.5 : 
     rate=0;

Answer 1

您需要为每个条件添加tar ===：

(tar === "EUR" || tar === "GBP" || tar === "USD")

或者，使用includes:

(["EUR", "GBP", "USD"].includes(tar))

Answer 2

您使用了 you 或 condition 而没有检查变量。就像"USD" || "GBP" 总是会返回true。

你还有另一个错误，你应该检查一下array.index(variable)。但你检查像

src.indexOf(arr)!=-1 && tar.indexOf(arr)!=-1

我已经添加了一个demo sn-p 请检查一下。

我使用了那个特殊的条件。

(tar === "EUR" || tar === "GBP" || tar === "USD"))

var tar = "DKK";
var src = "AUD";
var arr =["AUD","DKK","AED","BGN","CAD","CHF","CZK","DKK","HKD","HUF","ILS","INR",
       "JPY","MXN","NOK","NZD","PLN","QAR","RON","SAR","SEK","THB","TRY","ZAR"];
var res=
      ((src === "SGD" && tar === "AUD") || (src  === "AUD" && tar === "SGD"))?
      rate = 0.4 : 
      ((src === "SGD" && (tar === "EUR" || tar === "GBP" || tar === "USD")) ||
      ((src === "EUR" || "GBP" || "USD") && tar === "SGD"))?
      rate = 0.3:
      (arr.indexOf(src)!=-1 && arr.indexOf(tar)!=-1) ?
      rate = 0.5 : 
     rate=0;
     
     console.log(res)

Answer 3

如果条件匹配，您可以采用一个提前返回值的函数

function check() {
    const group = ["EUR", "GBP", "USD"];
    if (src === "SGD" && tar === "AUD" || src === "AUD" && tar === "SGD") return 0.4;
    if (src === "SGD" && group.includes(tar) || group.includes(src) && tar === "SGD") return 0.3;
    if (arr.includes(src) && arr.includes(tar)) return 0.5;
    return 0;
}

总之

var rate = src === "SGD" && tar === "AUD" || src === "AUD" && tar === "SGD"
        ? 0.4
        : src === "SGD" && ["EUR", "GBP", "USD"].includes(tar) || ["EUR", "GBP", "USD"].includes(src) && tar === "SGD"
            ? 0.3
            : arr.includes(src) && arr.includes(tar)
                ? 0.5
                : 0;