The Book of JavaScript, 2nd Edition

A Few More Details About Boolean Expressions

There are just a few more things you need to know about Boolean expressions before you can call yourself a Boolean master. You already know that you can create an if-then statement using code like this:

if (name == "thau") {
  alert("Hello, thau!");
}

This says, "If it is true that the variable name contains the string thau, put up an alert saying Hello, thau! " What you may not know is that you can store the value true or false in a variable and use it later. So, I could have done this instead:

var thisIsThau = (name == "thau");
if (thisIsThau == true) {
  alert("Hello, thau!");
}

The first line tests to see whether the variable name contains the string "thau". If it does, the test is true. This true value ...