How to: The ~ operator?

Question

I can't google the ~ operator to find out more about it. Can someone please explain to me in simple words what it is for and how to use it?

Answer 1

It is a bitwise NOT.

Most common use I've seen is a double bitwise NOT, for removing the decimal part of a number, e.g:

var a = 1.2; ~~a; // 1 

Why not use Math.floor? The trivial reason is that it is faster and uses fewer bytes. The more important reason depends on how you want to treat negative numbers. Consider:

var a = -1.2; Math.floor(a); // -2 ~~a; // -1 

So, use Math.floor for rounding down, use ~~ for chopping off ^{(not a technical term)}.

Answer 2

One usage of the ~ (Tilde) I have seen was getting boolean for .indexOf().

You could use: if(~myArray.indexOf('abc')){ };

Instead of this: if(myArray.indexOf('abc') > -1){ };

JSFiddle Example

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Additional Info: The Great Mystery of the Tilde(~)

Search Engine that allows special characters: Symbol Hound

Answer 3

It's a tilde and it is the bitwise NOT operator.

Answer 4

~ is a bitwise NOT operator. It will invert the bits that make up the value of the stored variable.

http://en.wikipedia.org/wiki/Bitwise_operations_in_C#Bitwise_NOT_.22.7E.22_.2F_one.27s_complement_.28unary.29