Is there a better way of writing v = (v == 0 ? 1 : 0); [closed]

Answer 1

Since 0 is a false value and 1 is a true value.

v = (v ? 0 : 1);

If you are happy to use true and false instead of numbers

v = !v;

or if they must be numbers:

v = +!v; /* Boolean invert v then cast back to a Number */

Answer 2

in general whenever you need to toggle between two values , you can just subtract the current value from the sum of the two toggle values :

    0,1 -> v = 1 - v
    1,2 -> v = 3 - v
    4,5 -> v = 9 - v 

Answer 3

I don't know why you want to build your own booleans? I like the funky syntaxes, but why not write understandable code?

This is not the shortest/fastest, but the most clearest (and readable for everyone) is using the well-known if/else state:

if (v === 0)
{
  v = 1;
}
else
{
  v = 0;
}

If you want to be really clear, you should use booleans instead of numbers for this. They are fast enough for most cases. With booleans, you could just use this syntax, which will win in shortness:

v = !v;

Answer 4

One more: v=++v%2

(in C it would be simple ++v%=2)

ps. Yeah, I know it's double assignment, but this is just raw rewrite of C's method (which doesn't work as is, cause JS pre-increment operator dosen't return lvalue.

Answer 5

List of solutions

There are three solutions I would like to propose. All of them convert any value to 0 (if 1, true etc.) or 1 (if 0, false, null etc.):

• v = 1*!v
• v = +!v
• v = ~~!v

and one additional, already mentioned, but clever and fast (although works only for 0s and 1s):

• v = 1-v

Solution 1

You can use the following solution:

v = 1*!v

This will first convert the integer to the opposite boolean (0 to True and any other value to False), then will treat it as integer when multiplying by 1. As a result 0 will be converted to 1 and any other value to 0.

As a proof see this jsfiddle and provide any values you wish to test: jsfiddle.net/rH3g5/

The results are as follows:

• -123 will convert to integer 0,
• -10 will convert to integer 0,
• -1 will convert to integer 0,
• 0 will convert to integer 1,
• 1 will convert to integer 0,
• 2 will convert to integer 0,
• 60 will convert to integer 0,

Solution 2

As mblase75 noted, jAndy had some other solution that works as mine:

v = +!v

It also first makes boolean from the original value, but uses + instead of 1* to convert it into integer. The result is exactly the same, but the notation is shorter.

Solution 3

The another approach is to use ~~ operator:

v = ~~!v

It is pretty uncommon and always converts to integer from boolean.

Answer 6

Well, As we know that in javascript only that Boolean comparison will also give you expected result.

i.e. v = v == 0 is enough for that.

Below is the code for that:

var v = 0;
alert("if v  is 0 output: " + (v == 0));

setTimeout(function() {
  v = 1;
  alert("if v  is 1 Output: " + (v == 0));
}, 1000);

JSFiddle: https://jsfiddle.net/vikash2402/83zf2zz0/

Hoping this will help you :)