JavaScript Immediately Invoked Function Expressions IIFE

المعرفة:: JavaScript
الحالة:: ملاحظة_مؤرشفة
المراجع:: The Complete JavaScript Course 2022 From Zero to Expert

IIFE¶

• Sometimes in JavaScript, we need a function that disappears right after it’s called once).
• This can be done by writing the function expression without assigning it to any variable then wrapping all of this into parentheses (transforming the statement into an expression).
• It’s useful for encapsulating data, since inner scope won’t be accessed by any outer one.
• This technique will be needed with async/await.

// IIFE  

// Normal function  
(function () {  
  console.log("This will never run again");  
  const isPrivate = 23;  
})();  

// Arrow function  
(() => console.log("This will ALSO never run again"))();  

• In modern JavaScript IIFE is not used widely because blocks can be used for achieving the same behavior with variables.

{  
  const isPrivate = 23;  
  var notPrivate = 46;  
}  
// console.log(isPrivate); // Can't be accessed  
console.log(notPrivate); // Can be accessed  

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