// It is simple code
var num = prompt("put number");
// This way is not worked
switch (num) {
case num > 0:
console.log("num++");
break;
case num < 0:
console.log(num-2);
break;
}
// But this worked
if (num > 0){
console.log(num++);
} else if (num < 0){
console.log(num -2);
}
My first way by "switch" is not worked but "if" method worked.
I tried all of thing for changing code or other ways but the same result.
Please guys help me.
Because the statement num > 0
inside you case
will return true
or false
. If you do this:
switch (true) {
case num > 0:
console.log("num++");
break;
case num < 0:
console.log(num-2);
break;
}
It will work.
Cases cannot be expressions, you must normalize your input first.
Although it is valid to place an expression in a case
, in this scenario a more tried-and-true way of dealing with this is to first normalize your input first.
You can determine direction for example:
var num = parseInt(prompt("put number"), 10); var direction = num < 0? -1: 1; switch (direction) { case 1: console.log("num++"); break; case -1: console.log(num - 2); break; }
The switch acts as a case switcher, meaning you cannot make comparisons to create cases, just list cases by case, and perform some function from this case. The if / else structure is suitable for making comparisons, as the expected result in the if call is always a boolean.
Example:
const a = 1;
if (a === 1) {
console.log('hello');
} else {
console.log('sad');
switch (a) {
case 1 : console.log('hello'); break;
default: console.log('sad'); break;
In your case, I recommend using if/else if/else, as it is more recommended.
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