JavaScript Advanced

Topics 

• JavaScript functions as first-class objects 
• Self-invoking function 
• Function scope 
• What is Closure? (Closure examples) 
• Why use Closure? (Closure usage examples) 
• Global object, non-global object, and “this”

JavaScript Functions as First-class Objects

A function is a first-class JavaScript Object (like String or Number object) 

• Functions are a bit like Java methods (like in Java) 
  • They contain statements for performing some tasks 
  • They have arguments and return values 
• A function is a first-class object in JavaScript (unlike in Java 7) 
  • Can be considered as a descendant of Object object 
  • Can do everything a regular JavaScript object can do such as having properties and their values 
  • Function objects can have other function objects as methods 
• A function behaves like a first-class object (unlike in Java 7) 
  • It can be saved into a variable (like String object) 
  • It can be passed as an argument to another function 
  • It can be returned as a object

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