条件运算符无法按预期在javascript中工作

Question

Below conditional operator is not working as expected I have included the conditions in scenario based.

If no src or tar matches, should be rate=0

If src is present in arr and is SGD and src is present in arr and is SGD (vice-versa), rate be 0.4

If src is present in arr and is "EUR" || "GBP" || "USD" "EUR" || "GBP" || "USD" "EUR" || "GBP" || "USD" and tar is present in arr and is "SGD" ,(vice-versa), rate be 0.3

If src is present in arr and tar is present in arr rate should be 0.5

scenario:

(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

You used you or condition without checking with a variable. just like "USD" || "GBP" "USD" || "GBP" which will return true always.

and you have another error you should check like array.index(variable) . but you checked like

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

I have added a demo snippet please check it.

I used that particular condition like.

(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 2

You need to add the tar === for every condition:

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

Alternatively, use includes :

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

Answer 3

You could take a function which returns a value early, if a condition match

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;
}

In short

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;