JavaScript function not passing my parameters to other function

Question

I'm having a problem where I'm trying to send parameters from one function to another, the function that receives the parameters uses a switch statement to evaluate it and returns it but it just returns what ever variable I put into it instead of "senior Master" for example. Here is the code I don't get what I'm doing wrong, just keep in mind I'm very new to coding maybe someone can give me some pointers. Thanks in advance.

function calculatexxx(x)  {
    let calculatexxx= x;
    switch (x) {
        case (x >= 2400):
            console.log("Senior Master");
            break;
        case (2399 > x > 2200):
            console.log("National Master");
            break;
        case (2199 > x> 2000):
            console.log("Expert");
            break;
        case (1999 > x> 1800):
            console.log("Class A");
            break;
        case (1799 > x> 1600):
            console.log("Class B");
            break;
        default:
            console.log("Error input not valid");

    return(x);

    }
}
function displayxxx() {
    console.log("Your Rank is: " + calculatexxx(2400)); // 

}
displayxxx();

Your `return` statement should be **outside** the `switch` block. — Pointy, Nov 07 '19 at 15:56
I suggest you look up 1. how `switch` statement is used. This is not the correct way - you are better of with an `if/else` chain. 2. how comparison operators work. `1799 > x> 1600` does not check if `x` is between `1799` and `1600`. — VLAZ, Nov 07 '19 at 15:57
You really should not be using a switch for ranges. (and range check is not doing what you think it is doing. It is `((2399 > x) > 2200)` so it would be `(true > 2200)` or `(false > 2200)` https://stackoverflow.com/questions/6454198/check-if-a-value-is-within-a-range-of-numbers — epascarello, Nov 07 '19 at 15:59

Nina Scholz · Accepted Answer · 2020-09-04T11:28:26.863

Just have a look to this expression

2399 > x > 2200

and take three values, like zero, 2300 (this should return true) and 10000.

The expression is executed in order of appearance, because of the same operator.

      x     2399 > x     value   value > 2200     yield     result
--------  ------------  -------  ------------  ----------  --------
      0   2399 >     0    true    true > 2200   1 > 2200     false
   2300   2399 >  2300    true    true > 2200   1 > 2200     false
 100000   2399 > 10000   false   false > 2200   0 > 2200     false

The final result is always false, because the first part returns a boolean value and the converted value is never greater than the last value.

Conclusion

Take two comparisons connected with logical AND &&:

2399 > x && x > 2200

For taking a switch statement, you need to take the comparison value in the condition part and in the cases the other condition. And by returning directly, you could omit break, because the function ends with it.

function calculate(x) {
    switch (true) {
        case x >= 2400: return "Senior Master";
        case x >= 2200: return "National Master";
        case x >= 2000: return "Expert";
        case x >= 1800: return "Class A";
        case x >= 1600: return "Class B";
    }
    return "Error input not valid";
}

function display() {
    console.log("Your Rank is: " + calculate(2400));
}

display();

Another solution could be to use continuing if statements and return early. This approach is better, because it does not missuse the original idea of select where two values have to be compared.

function calculate(x) {
    if (x >= 2400) return "Senior Master";
    if (x >= 2200) return "National Master";
    if (x >= 2000) return "Expert";
    if (x >= 1800) return "Class A";
    if (x >= 1600) return "Class B";
    return "Error input not valid";
}

function display() {
    console.log("Your Rank is: " + calculate(2400));
}

display();

Wow, I've never realised you could do that with a switch statement. Somehow it seems so wrong but at the same time awesome. — radulfr, Nov 07 '19 at 16:08
thanks very much this was very helpful, this is homework so i needed to use a switch statement. — steakman, Nov 08 '19 at 10:45

score 0 · Answer 2 · answered Nov 07 '19 at 16:02

Firstly you'll have to change your switch conditions from 1799 > x > 1600 to 1799 > x && x >= 1600

Then instead of console.logging in the case itself, you should return "Expert" etc so the concatination in the function displayxxx actually does something.

score 0 · Answer 3 · answered Nov 07 '19 at 16:03

can you try this.

function calculatexxx(x)  {

        if (x >= 2400){
            console.log("Senior Master");
           }
           else if (2399 > x > 2200){
            console.log("National Master");
        }
        else if (2199 > x> 2000){
            console.log("Expert");
           }
        else if (1999 > x> 1800){
            console.log("Class A");
            }
        else if (1799 > x> 1600):
            console.log("Class B");
            }
        else{
            console.log("Error input not valid");
            }/////////////

    return(x);

    }
}
function displayxxx() {
    console.log("Your Rank is: " + calculatexxx(2400)); // 

}
displayxxx();

thanks for the help, i need to use a switch statement though. — steakman, Nov 08 '19 at 10:59

JavaScript function not passing my parameters to other function

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