Javascript && operator versus nested if statements: what is faster?
The performance difference is negligible. The && operator won't check the right hand expression when the left hand expression evaluates false. However, the & operator will check both regardless, maybe your confusion is caused by this fact.
In this particular example, I'd just choose the one using &&, since that's better readable.
If you're concerned about performance, then make sure that a==b is more likely to fail than c==d. That way the if statement will fail early.
Like nested ifs, && is lazy.
The expression a && b will only evaluate b if a is truthful.
Therefore, the two cases should be completely identical, in both functionality and performance.