Why does "alert(3>2>1)" alert "false" [duplicate]

If you add parentheses to show how JavaScript is interpreting it, it gets much clearer:

alert( (3 > 2) > 1 );

Let's pick this apart. First, it evaluates 3 > 2. Yes, three is greater than two. Therefore, you now have this:

alert( true > 1 );

true is coerced into a number. That number happens to be 1. 1 > 1 is obviously false. Therefore, the result is:

alert( false );

First 3>2 evaluates to TRUE, which is probably implicitly converted to 1, so you end up with 1>1, which is FALSE.

You might want an error here, but Javascript is very weakly typed, so it will try to do implicit conversions, without complaining.

EDIT:

So you're asking why the programming language syntax does not always coincide with the mathematical notation? I would say (1) they have different priorities and (2) it makes more sense for the compiler to do it another way.

This is not uncommon though:

• "x = 3" (statement) and x = 3 (assignment)
• "x >> 1" (much more than 1) and x >> 1 (bitshift)
• "a | b" (a divides b) and a | b (bitwise OR).

The list goes on...

It's being evaluated like:

+(3>2) > 1

Which is the same as:

+(true) > 1

Which finally is:

1 > 1 = false

But hey, at least 3 > 2 > 0 will work ;)