Javascript setTimeout (0), closures

SetTimeout are often used to delay the running of a function, using the method of

SetTimeout (function () {

...

}, timeout);

Sometimes settimeout (function...,0) is used for asynchronous processing, for example

function f () {

...//Get ready

SetTimeout (function () {

....//Do something

}, 0);

return ...;

}

function f is returned before the function processor set by settimeout;

When you are using asynchronous processing. Especially when using the closure feature. be particularly careful;

for (var i = 0; i < i++) {

SetTimeout (function () {

Console.log (i);

}, 0);

}

For the first time to use such a way of students. It is very likely that the program will print 0 ... 9. The results are indeed printed 10 10;

The problem is that when the loop is complete, the function gets run, and I has become 10,console.log (i) using 10!

Increase your aim is to print 0 ... 9, it is possible to use a function reference to save the 0....9 in a different way (actually using closures)

for (var i = 0; i < i++) {

SetTimeout ((function (i){

return function () {

Console.log (i);

}

}) (i), 0);

}

Javascript setTimeout (0), closures