What does && mean in Javascript when it's outside of an if statement? (Context inside)

Question

I was cleaning up some code on my homepage and found one of my jquery functions I had written like so:

$(function(){
        var hash = window.location.hash;
        hash && $('[id^=search] a[href="' + hash + '"]').tab('show');

        $('[id^=search] a').click(function (e) {
        $(this).tab('show');
        var scrollmem = $('body').scrollTop();
        window.location.hash = this.hash;
        $('html,body').scrollTop(scrollmem);
  });
});

This particular piece changes tabs on the homepage when an external link contains a hash that matches with any hashes in my navigation. I hadn't worked with this snippet in a while (this was one of the first things I ever did for my website.) and I cannot for the life of me work out in my brain what hash && $('[id^=search] a[href="' + hash + '"]') translates to. If I were to think of it as plain english, what would it be?

Answer 1

It is like if statement:

if (hash) {
  $('[id^=search] a[href="' + hash + '"]').tab('show');
}

This is equivalent to:

hash && $('[id^=search] a[href="' + hash + '"]').tab('show');

If the condition evaluates to true then only the next statement after && is executed.

Answer 2

The output of hash && $('[id^=search] a[href="' + hash + '"]').tab('show') will be the same if you put the entire thing inside an if.

Answer 3

The logical operator && will evaluate the second operand only if the first one is truthy so it is the same as

if(hash)
    $('[id^=search] a[href="' + hash + '"]').tab('show');

so the $('[id^=search] a[href="' + hash + '"]').tab('show'); will get executed only if there is a hash value present in the location.