Comparison & Logical Operators

The previous page looked complicated because of a phenomena called information overload. And to deal with that we have break the problem down. So, let me do that for you.

• Logical

  • NOT (!)
  • OR (||)
  • AND (&&)

• Comparison

  • Equal to (== & ===)
  • Not Equal to (!= & !==)
  • Less than and Less than equal to (< & <=)
  • Greater than and Greater than equal to> & >=

NOTE: There was specific reason why I overloaded you with that much information in the last page. Because in real-life you'll only see code like that, actually even worse than that. The key is not get over-whelmed but go line-by-line. Identify what you know, and predict the unknown.

Logical

If you're aware of the terms like truth table, logical gate. Then next 3 operator will be self explanatory to you. If not, then don't worry they are very simple (and important).

NOT (!)

Let's look only at the NOT(!) operator.

console.log('!true = ', !true);
console.log('!false = ', !false);

Did you get it? If not, try reading it out !true => NOTtrue. Meaning if it is not true, then it must be false. Therefore, If you put ! before true, it makes it false and vice-versa. But that's for boolean, how about numbers? Try guessing the output before running the example.

console.log('!7 = ', !7);
console.log('!false = ', !0);

Did you get it? This is happening because in javascript every value is either Truthy or Falsy. You can either play with code and figure out, or read the mentioned link.

Remember all the Falsy values, all the other value should be Truthy.

Before proceeding with the rest of Logical operators, we'll understand the Comparison operators.