Best example of falsey is :

if (!y)
{
//do something
}

I have a question : Is example given below belongs to Truthy/Falsey or not? I am little confused.

if (y==7)
{
//do something
}

1. I have to say that when I saw your name in the title I read “Pseldoy” (as pseudo is falsey).

2. I have found that truthy (and falsey) are adjectives (like true) instead of nouns (like truth). That’s why I arrived at your post. I became sure when I read “the falsey value that you’re looking for”. Thank’s!

3. In Ruby I want to create an object which is falsey, but I can’t. I wish I had a ToBoolean-equivalent method to overload, but I haven’t that AFAIK.

4. Great article! I’ve appreciated it very much! Thank’s again.

5. Great comments, too! 🙂

6. I loved the moving background.

The way I think of it, truthiness/falsiness is determined when evaluating the expression and comparing it to values that could be considered “nothing.” Truth/falsity is determined by looking at whether the expression evaluates to a primitive boolean value exactly, and then comparing its value to true or false. I am still learning about this, but I don’t believe that there is any _implicit_ casting to booleans in JavaScript.

As others have said, the tricky part is that both conditional blocks and variable assignments can both use expressions that are evaluated for truthiness/falsiness (or they can use true/false boolean expressions). Once you really understand that, everything makes a little more sense.

Jamie and Mathias: excellent point about if(x==true) being different to if(x)!

DZ, new Boolean instantiates a new Boolean object, while Boolean (without the new operator) only casts the value to a boolean (primitive).

From the spec:

15.6.1 The Boolean Constructor Called as a Function
When Boolean is called as a function rather than as a constructor, it performs a type conversion.

new Boolean(true); // <- Calling `Boolean` as a constructor
Boolean(true); // <- Calling `Boolean` as a function