Javascript Simple Boolean Arithemetic

Question

I’ve heard of boolean arithmetic and thought of giving it a try.

alert (true+true===2)  //true
alert (true-true===0)  //true

So algebra tells me true=1

alert (true===1)  //false :O

Could someone explain why this happens?

Answer 1

=== is the strict equality operator. Try == operator instead. true==1 will evaluate to true.

The strict equality operator === only considers values equal if they have the same type. The lenient equality operator == tries to convert values of different types, before comparing like strict equality.

Case 1:

In case of true===1, The data type of true is boolean whereas the type of 1 is number. Thus the expression true===1 will evaluate to false.

Case 2:

In case of true+true===2 and true-true===0 the arithmetic operation is performed first(Since + operator takes precedence over ===. See Operator Precedence) and then the result is compared with the other operand.

While evaluating expression (true+true===2), the arithmetic operation true+true performed first producing result 2. Then the result is compered with the other operand. i.e. (2==2) will evaluate to true.

Answer 2

Because comparing data TYPE and value (that's what operator '===' does ), TRUE is not exactly the same as 1. If you changed this to TRUE == 1, it should work fine.

Answer 3

first 2 expression are true because you are using expression (true+true) (true-true) it convert type of a value first due to expression and check equality with "===", toNumber and toPrimitive are internal methods which convert their arguments (during expression ) this is how conversion take place during expression

That's why true+true equal to the 2

In your third expression you are using === this not convert arguments just check equality with type, to make it true both values and there type must be same.

Thats all

Answer 4

At the beginning, you're doing bool + bool. The + operator takes precedence over the === operator so it's evaluated first. In this evaluation, it's converting the booleans to their number forms. Run console.log(true + true); and this will return 2. Since you're comparing the number 2 to the number 2, you get a return value true with the strict equality.

When you're just comparing true === 1, like everyone else said you're comparing the boolean true to the number 1 which is not strictly equal.