Javascript – Multiple Ternary Operators

conditional-operatorjavascript

I need a bit of syntax help with a ternary operator which will help me to put the correct marker icons on to my good map. I have three areas 0, 1 and 2 which have unique icons 0, 1 and 2.

I used to have just two areas so this ternary operator worked fine;

var icon = (area == 1) ? icon1 : icon0;

Now I need to add an additional third icon (icon2) for area2.

I've tried various methods but just can't seem to get it right.

Best Answer

The syntax would be:

var icon = (area == 1) ? icon1 : (area == 2) ? icon2 : icon0;

But this is starting to get complicated. You may well be better off just creating a function to do this work instead:

var icon = getIcon(area);

function getIcon(area) {
  if (area == 1) { 
    return icon1; 
  } else if (area == 2) { 
    return icon2; 
  }

  return icon0;
}

Related Solutions

Python – Does Python have a ternary conditional operator

Yes, it was added in version 2.5. The expression syntax is:

a if condition else b

First condition is evaluated, then exactly one of either a or b is evaluated and returned based on the Boolean value of condition. If condition evaluates to True, then a is evaluated and returned but b is ignored, or else when b is evaluated and returned but a is ignored.

This allows short-circuiting because when condition is true only a is evaluated and b is not evaluated at all, but when condition is false only b is evaluated and a is not evaluated at all.

For example:

>>> 'true' if True else 'false'
'true'
>>> 'true' if False else 'false'
'false'

Note that conditionals are an expression, not a statement. This means you can't use assignment statements or pass or other statements within a conditional expression:

>>> pass if False else x = 3
  File "<stdin>", line 1
    pass if False else x = 3
          ^
SyntaxError: invalid syntax

You can, however, use conditional expressions to assign a variable like so:

x = a if True else b

Think of the conditional expression as switching between two values. It is very useful when you're in a 'one value or another' situation, it but doesn't do much else.

If you need to use statements, you have to use a normal if statement instead of a conditional expression.

Keep in mind that it's frowned upon by some Pythonistas for several reasons:

The order of the arguments is different from those of the classic condition ? a : b ternary operator from many other languages (such as C, C++, Go, Perl, Ruby, Java, Javascript, etc.), which may lead to bugs when people unfamiliar with Python's "surprising" behaviour use it (they may reverse the argument order).
Some find it "unwieldy", since it goes contrary to the normal flow of thought (thinking of the condition first and then the effects).
Stylistic reasons. (Although the 'inline if' can be really useful, and make your script more concise, it really does complicate your code)

If you're having trouble remembering the order, then remember that when read aloud, you (almost) say what you mean. For example, x = 4 if b > 8 else 9 is read aloud as x will be 4 if b is greater than 8 otherwise 9.

Official documentation:

Vb.net – conditional ternary operator in VB.NET

Depends upon the version. The If operator in VB.NET 2008 is a ternary operator (as well as a null coalescence operator). This was just introduced, prior to 2008 this was not available. Here's some more info: Visual Basic If announcement

Example:

Dim foo as String = If(bar = buz, cat, dog)

[EDIT]

Prior to 2008 it was IIf, which worked almost identically to the If operator described Above.

Example:

Dim foo as String = IIf(bar = buz, cat, dog)

Best Answer

Related Solutions

Python – Does Python have a ternary conditional operator

Vb.net – conditional ternary operator in VB.NET

Related Topic