Use self-executing anonymous functions to solve the problem of using closures in for loops_javascript skills

This code outputs 10 10s instead of the expected 0 to 9, because the closure contains a reference to i, and then i has become 10 when the function is executed

function f1(){
for(var i = 0; i < 10; i++) {
setTimeout(function() {
alert(i); 
}, 1000);
}
}
f1();

To solve the above problems, you can use self-executing anonymous functions

function f2(){
for(var i = 0; i < 10; i++) {
(function(e) {
setTimeout(function() {
alert(e); 
}, 1000);
})(i);
}
}
f2();

The anonymous function here takes i as a parameter, and the e here will have a copy of i, and the reference is a reference to e, which avoids the above problem