Closure Analysis of javascript Learning

In ECMAScript, all declared variables seen outside the function at the function declaration can be accessed inside the function.Final value!

Closure functions can only access the final value of a variable !!!

Eg:

Function fnTest (arr ){
For (var I = 0; I <arr. length; I ++ ){
Arr [I] = function () {alert (I + "|" + arr [I]);};
}
}
Var arr = [0, 1, 2, 3];
FnTest (arr );
For (var I = 0; I <arr. length; I ++ ){
Arr [I] (); // always output 4 and an undefinedBecause the I value is 4 after the function exits, the accessed value is only 4

// The result is continuous.Four "4 | undefined" are displayed"
}

 Not only can the variable values outside the closure be accessed in the closure, but also its values can be set.

Eg:

Function fnTest (){
Var a = "June ";
Return {
Set: function (param ){A = param},
Get: function () {return}
};
}
Var obj = fnTest ();
Alert (obj. get ());//June is displayed.

Obj. set (586 );
Alert (obj. get ());//586