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javascriptif-statementconditional-statements
bluehermit21
bluehermit21

Reputation: 31

Can conditional operator " ? : " be considered as an alternative to if-else statement in JavaScript?

Someone asked me this question in a workshop and about what are some alternative to the if-else statement in JavaScript except from switch. Is the conditional operator just a shorthand for if-else?

Upvotes: 2

Views: 2291

Answers (2)

georg
georg

Reputation: 215029

JS is a "phrasal" programming language and strictly separates between expressions (values and operators) and statements. ? is an operator and can be used within an expression:

a = x ? y : z

while if cannot, because it's a statement:

a = if (x)  ... // syntax error

On the other hand, every expression is also a statement, when used in an appropriate context:

 while (1)
    a = x ? y : z;

so it's fair to say that ? is "broader" than if because it can be used in both contexts. Which of course doesn't mean it should (rather not).

If you're interested in other ways to express conditional logic, you can do that with boolean operators:

 a && do_something() // "if a do_something()"
 b || do_something() // "if not b do_something()"

although such uses are mostly considered bad style.

Upvotes: 5

Peter B
Peter B

Reputation: 24280

It is somewhat shorthand, but only in case of returning / obtaining a value or object from two possible expressions.

Examples:

// inside a function
if (condition) { return X; } else { return Y; }

// Functionally equivalent to
return condition ? X : Y;

var tmp;
if (condition) { tmp = GetFoo(123); } else { tmp = GetBar(456); }
DoSomething(tmp);

// Functionally equivalent to
DoSomething(condition ? GetFoo(123) : GetBar(456));

If there are no return values, there is still an equivalency but people might scream at you for doing this:

if (condition) { A(); } else { B(); }
// *shudder*
condition ? A() : B();

And the following are impossible or at least hard to change into ?:: 

if (condition) { A(); return true; } else { B(); return false; }
// Reason: code blocks contain multiple statements

if (condition) { tmp = GetFoo(123); }
// Reason: no "else"-block (or you need to construct/invent one)

Upvotes: 0

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