Exploring the magic of the (!!!) operator in JavaScript!

Question

Exploring the magic of the (!!!) operator in JavaScript!

The !! operator proves to be quite helpful when converting non-boolean data types into Boolean values, mainly for "True" conditions.

However, when it comes to false conditions, is using !!! necessary?

javascript

Answer 1

Answer №1

Just one exclamation mark is sufficient :)

!1 // false
!0 // true

Answer 2

Just one exclamation mark is sufficient :)

!1 // false
!0 // true

Answer 3

Answer №2

!! isn't considered an operator on its own; it's simply a technique for utilizing JavaScript's logical NOT (!) operator.

When you want to convert x to a boolean, using !!x is effective because double negating a boolean will result in the original boolean value, and !x first converts x to a boolean before performing the negation.

In a similar fashion, !!!x converts x to a boolean and negates it three times unnecessarily, as one negation would achieve the same result. Therefore, it's recommended to stick with using !x rather than !!!x.

Answer 4

!! isn't considered an operator on its own; it's simply a technique for utilizing JavaScript's logical NOT (!) operator.

When you want to convert x to a boolean, using !!x is effective because double negating a boolean will result in the original boolean value, and !x first converts x to a boolean before performing the negation.

In a similar fashion, !!!x converts x to a boolean and negates it three times unnecessarily, as one negation would achieve the same result. Therefore, it's recommended to stick with using !x rather than !!!x.

Answer 5

Answer №3

that explanation pertains to situations with "True" conditions.

No, it applies to any value. When you use the double not operator - !!, it will convert any value into its equivalent Boolean value.

But why does this work? Well, the not operator simply flips the Boolean value to its opposite. For example:

0    // is considered falsy
!0   // becomes true
!!0  // becomes false

'foo'    // is considered truthy
!'foo'   // becomes false
!!'foo'  // becomes true

Each additional application of the not operator will toggle the value again. Therefore, !!! is equal to !, and !!!! is equal to !!, and so on.

Answer 6

that explanation pertains to situations with "True" conditions.

No, it applies to any value. When you use the double not operator - !!, it will convert any value into its equivalent Boolean value.

But why does this work? Well, the not operator simply flips the Boolean value to its opposite. For example:

0    // is considered falsy
!0   // becomes true
!!0  // becomes false

'foo'    // is considered truthy
!'foo'   // becomes false
!!'foo'  // becomes true

Each additional application of the not operator will toggle the value again. Therefore, !!! is equal to !, and !!!! is equal to !!, and so on.

Answer 7

Answer №4

let checkBool = 0;
   checkBool //0
  !checkBool //true
 !!checkBool //false
!!!checkBool //true - once more

Similarly:

let checkBool = 1;
   checkBool //1
  !checkBool //false
 !!checkBool //true
!!!checkBool //false - again

Using the triple negation ( !!! ) is redundant. The double negation ( !! ) comes in handy when:

We want a Boolean value, for example: !!5 => true;
We want to simplify false as !1 or true as !0.
1. or avoid using an extra wrapper.

Answer 8

let checkBool = 0;
   checkBool //0
  !checkBool //true
 !!checkBool //false
!!!checkBool //true - once more

Similarly:

let checkBool = 1;
   checkBool //1
  !checkBool //false
 !!checkBool //true
!!!checkBool //false - again

Using the triple negation ( !!! ) is redundant. The double negation ( !! ) comes in handy when:

We want a Boolean value, for example: !!5 => true;
We want to simplify false as !1 or true as !0.
1. or avoid using an extra wrapper.

Answer 9

Answer №5

This response addresses your inquiry with precision

It appears that the use of !!!x is likely inverting a boolean conversion !!x:

var myBool = Boolean("false");  // Evaluates to true

var myBool = !!"false";  // Also evaluates to true

"Any non-empty string will return true when evaluated"

Therefore !!!"false"; // Returns false

This topic should be taken seriously. Node.js (downloaded 5 days ago) utilizes this technique in Assert.js, for instance:

function ok(value, message) {
  if (!!!value) fail(value, true, message, '==', assert.ok);
}
assert.ok = ok;

UPDATE: It seems they may have done it for better code readability as per their usual practice, since !value alone could suffice.

UPDATE: There has been a change in Node's implementation. It remains unclear why the version I downloaded five days ago still uses !!!value instead of !value on GitHub.

UPDATE: This link provides insight into the reasoning behind it.

Answer 10

This response addresses your inquiry with precision

It appears that the use of !!!x is likely inverting a boolean conversion !!x:

var myBool = Boolean("false");  // Evaluates to true

var myBool = !!"false";  // Also evaluates to true

"Any non-empty string will return true when evaluated"

Therefore !!!"false"; // Returns false

This topic should be taken seriously. Node.js (downloaded 5 days ago) utilizes this technique in Assert.js, for instance:

function ok(value, message) {
  if (!!!value) fail(value, true, message, '==', assert.ok);
}
assert.ok = ok;

UPDATE: It seems they may have done it for better code readability as per their usual practice, since !value alone could suffice.

UPDATE: There has been a change in Node's implementation. It remains unclear why the version I downloaded five days ago still uses !!!value instead of !value on GitHub.

UPDATE: This link provides insight into the reasoning behind it.

Exploring the magic of the (!!!) operator in JavaScript!

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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