Difference between "if (foo) bar();" and "foo && bar();" [duplicate]

Question

Is there any difference between the following two snippets, or any reason to use one over the other?

if (foo) {
    bar();
}

 

foo && bar();

Answer 1

The second form is known as short-circuit evaluation and results in exactly the same as the first form. However the first form is more readable and should be preferred for maintainability.

This type of short-cuircuit evaluation is often seen in if-statements, where the right hand is conditionally evaluated. See the example below; bar is only evaluated if foo evaluates to true.

if (foo && bar()) {
    // ...
}

Answer 2

The version foo && bar() is an expression, and thus has a value:

var result = foo && bar();

When using the if version, the above might look like this:

var result;
if (foo) {
    result = bar();
}

which is more verbose.