Js closure problem

for(var i=0;i<10;iPP){
    fnArr[i]=(function(){
        var n=i;
        return function(){
            return n
        }
    })();

}
for(var i=0;i<10;iPP){
        (function(){
            var n=i;
        fnArr[i]=function(){
            return n
        };
        })()
    }

all of the above allow fnArr [3] to output 3 instead of 10, but why do you have to declare nSecreti? If you go to this sentence, you will not be able to output it correctly

.
Javascript
Mar.03,2021

the outer and inner layers are two scopes, and each variable access is the closest. If there is no sentence var n = I , the top-level scope will be accessed, and by this time I has reached 10

if you do not use var I to receive the value of I and return I directly, then the later function cannot find the value of I when it is running, so it will go back to the upper scope to look for it, while the upper scope loop ends, and the value of I is 10, so it will always return 10.

and use var nimi . I want to save the value of I in each loop in the interior of the self-tuning function, and if the value of n cannot be found when the return function is running, it will also go to the upper scope to find the value of n inside the self-tuning function, which corresponds to 0-9 respectively.

can be changed in this way, and the effect is the same 

for(var i=0;i<10;iPP){ 
  fnArr[i]=(function(i){ 
    return function(){ 
      return i
    } 
  })(i); 
}

Previous: Why does the angular2 jump to a new route not trigger the lifecycle function, but only the constructor?

Next: How to realize service degradation

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
© 2021 CodesHelper
Advertising Contact us About us
Menu