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CODE EXAMPLE FOR JAVASCRIPT

!! js

We use the double bang operator (!!) to check if a value is `truthy` or `falsy`.
That means to check if a value is considered `true` or `false` by JavaScript.

We use it when we need a boolean value according to a non-boolean value,
for example if we need the value `false` if a string is empty, `true` otherwise.
                                 
str = "Double bang operator"; // not empty strings are considered true by JS
console.log(str == true); // false
console.log(!!str); // true
str = ""; // empty strings are considered false by JS
console.log(str == false); // true
console.log(!!str); // false

Truthy values :
 - Objects : {}   // even empty objects
 - Arrays : []   // even empty Arrays
 - Not empty strings : "Anything"
 - Numbers other than 0 : 3.14
 - Dates : new Date()
Falsy values :
 - Empty strings : ""
 - 0
 - null
 - undefined
 - NaN
Source by www.roblox.com #
 
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Tagged: #js
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