Roman Roman - 4 months ago 11
Javascript Question

multiple expressions in one switch statement

It is my first time using the

switch
statement in Javascript. Is there a way to evaluate multiple conditions one switch statement, like so:

var i = 1;
switch(i && random(1)<0.3) {
case (1):
//code block
break;
case (2):
//code block
}


So that the code blocks would execute if both of the conditions were true?

Answer

You could do something like this:

var i = 1;
switch((i==1) + (Math.random(1)<0.3)*2) {
    case 0:
        //code block when neither is true
         break;
    case 1:
        //code block when only i == 1
         break;
    case 2:
        //code block when only random(1)<0.3
         break;
    case 3:
        //code block when both i==1 and random(1)<0.3
        break;
} 

... but it is not really the nicest code, and can easily lead to mistakes when one of the tested expressions is anything else than 0 or 1 (false or true).

It is better to use if ... else constructs to deal with this:

var i = 1;
var small = Math.random(1)<0.3;
if (i==1) {
    if (small) {
        //code block when both i==1 and random(1)<0.3
    } else {
        //code block when only i == 1
    }
} else if (small) {
    //code block when only random(1)<0.3
} else {
    //code block when neither is true
}