Could someone explain to me what this line of code means:
function1(num) ? 13 : 12;
I think it means
if function1(num) = 12 then function1(num) = 12
What is your input?
That code is incomplete because it isn’t doing anything with the value so with just that it would be equivalent to
if (function1(num)) 13;
else 12;
In order to actually do something with the numbers you’d need to assign the whole thing to something for example:
x = function1(num) ? 13 : 12;
which is the same as
if (function1(num)) x = 13;
else x = 12;
You could easiy test it for yourself by picking two different values for num where one causes function1() to return true and the other has it return false.
x = function1(num) ? 13 : 12;
So some values:
if function1(num) =13
x=12
if function1(num) = 12
x = 12
if function1(num) = 5
x = 5
if function1(num) = 15
x = 15
if function1(num) = n
x = n unless n=13 then x=12
This is just ternary operator.
If num is TRUE or 1 assign 13 else assign 12
It is the simplified version of if and else.
Just the basic.
It all depends on what is in function1.
If function 1 is defined as:
function1 = function(num) {return isFinite(num);};
then
x = function1(num) ? 13 : 12;
would set x to 13 if num contains a finite number and to 12 if it contains infinity or something other than a number.
If function 1 is defined as:
function1 = function(num) {return false;};
then it would set x to 12 regardless of what is in num.
You haven’t showed us your function1() so what num needs to be to return true (and so set a value of 13) and what it needs to be to return false (and set a value of 12) are completely unknown to us.
If function 1 is defined as:
function1 = function(num) {return 12===num ? true : false;};
then
x = function1(num) ? 13 : 12;
would set x to 13 if num is 12 and set x to 12 if num is anything at all except 12.
First understand that the comparison operator is == not =, otherwise you’ll soon be back asking another question.
I still don’t think you understand:
The statement
function1(num) ? 13 : 12;
evaluates to 13 when function1(num) returns a non-zero value, otherwise 12.
Or more accurately, when function1(num) returns a non-falsy value, then the above code evaluates to 13.
If function1(num) is a falsy value (false, undefined, null, NaN, 0, “”), then the above code evaluates to 12.
The question mark is a conditional operator.
condition ? expr1 : expr2
You can see that above link for further details.