Javascript: which is better, conditional return or conditional block? [closed]

Suppose I have a function which returns nothing, with code that should execute only if a condition is not met. What is best from a performance/efficiency perspective:

1. to begin with a conditional return statement:

function f() {
    if (condition) return;
    // Do something...
}

2. or to use a conditional block:

function f() {
    if (!condition) {
        // Do something...
    }
}

?