In javascript what is the difference between operator '~' and '!'

Question

I am out of theories, i don't know what else to say.

So far i always thought that both changed the value to false.

But, !, changes to true/false.

While, ~ , changes to negative number with 1 less so 2 become -3. Why and how.

take a look at [this answer](http://stackoverflow.com/a/12337406/390819). — Cristian Lupascu, Jul 04 '13 at 18:08
question: how do you know that 00000000000000000000000000001001 is 9.Why there are 32 bits, is it only javascript related? — Muhammad Umer, Jul 04 '13 at 18:13
@MuhammadUmer: You clearly haven't clicked the [link](http://www.ecma-international.org/ecma-262/5.1/#sec-11.4.8) in my answer (or the one provided by Praveen): *"The production UnaryExpression : `~` UnaryExpression is evaluated as follows: 1. Let `expr` be the result of evaluating UnaryExpression. 2. Let oldValue be **`ToInt32(GetValue(expr)).`** 3. Return the result of applying bitwise complement to `oldValue`. The result is a **signed 32-bit integer**."* — Zeta, Jul 04 '13 at 18:15

score 1 · Answer 1 · answered Jul 04 '13 at 18:08

1

~ (Bitwise NOT)

Performs the NOT operator on each bit. NOT a yields the inverted value (a.k.a. one’s complement) of a. The truth table for the NOT operation is:

a   NOT a
0   1
1   0

Example

9 = 00000000000000000000000000001001 (base 2)
               --------------------------------
~9 = 11111111111111111111111111110110 (base 2) = -10 (base 10)

Answer sourced from The tilde ~ operator in JavaScript.

answered Jul 04 '13 at 18:08

Praveen Kumar Purushothaman

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@MuhammadUmer When you are doing bitwise operations and not boolean operations! :) – Praveen Kumar Purushothaman Jul 04 '13 at 18:42
@MuhammadUmer common case is to unset nth bit in an integer: `value & ~(1 << n)` the value will have nth bit unset (0-based indexing from the right) – Esailija Jul 04 '13 at 19:15
man bitwise whole thing is beyond me..I did never get the whole base 2 to base 10 thing down ever. – Muhammad Umer Jul 04 '13 at 19:43

score 0 · Answer 2 · answered Jul 04 '13 at 18:08

! is a logical operator, its result is either true or false, while ~ is a bitwise operator.

If you don't understand why ~number is -number - 1 have a look at two's complement.

I am out of theories, i don't know what else to say.

In this case have a look at the language's documentation.

score 0 · Answer 3 · answered Jul 04 '13 at 18:09

! is a boolean operator, it negates the result of a boolean expression.

~ on the other side is the bitwise not operator, which basically means, it flips all the bits in your operand, say, -1 which is represented by all 1 bits to 0 (which means 0 bits are set).

In javascript what is the difference between operator '~' and '!'

3 Answers3