Multiple assignments inside if-statement

Question

Why can't I do this:

var fooElement, barElements;
if(fooElement = document.getElementById('foo') && barElements = fooElement.getElementsByTagName('bar') && barElements[0] && barElements[0].onclick)
{
    console.log(barElements[0].onclick);
}

This won't work either:

var foo, bar;
if(foo = true && bar = true)
{
    console.log('yay');
}

Answer 1

Try this (it should give you a clue):

var foo, bar;
if((foo = true) && (bar = true))
{
    console.log('yay');
}