JS --- Advanced Closure

Closure

 

Concept of closures: the function A, a function B, function B can access function A defined variables or data, at this time the closure is formed (this sentence temporarily stringency)

• Closure mode: Mode closure function, object model closure
• Action closures: cache data, to extend the scope chain
• Closure of the advantages and disadvantages: the data cache
• Closures

 

Mode closure function: a function in a function

    // function closure mode: there is a function in a function 
    function F1 () {
       var NUM = 10 ;
       // declare function of 
      function F2 () { 
        the console.log (NUM); 
      } 
      // function calls 
      F2 () ; 
    } 
    F1 ();

    function f1 () { 
      were num = 10 ; 
      return function () { 
        console.log (num); 10 // 
        return num;  }  } 
 Was ff = f 1 ();  were result = ff (); console.log (result); // 10

 

 

 Closure object model: there is a target function

    function f3 () {
       were num = 10 ;
      was obj = { 
        Age: num 
      }; 
      console.log (obj.age); // 10 
    } 
    f3 ();

 

    function f2 () {
       were num = 100 ;
      Return { 
        Age: num 
      } 
    } 

    were obj = f2 (); 
    console.log (obj.age);