Javascript setTimeout (0), closures

SetTimeout is often used to defer execution of a function, using the

SetTimeout (function () {

...

}, timeout);

SetTimeout (function...,0) is sometimes 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 using asynchronous processing, especially when using the closure feature, be especially cautious;

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

SetTimeout (function () {

Console.log (i);

}, 0);

}

For students who first use this method, it is 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 is executed, and I has become 10,console.log (i) using 10!

Join your goal is to print 0 ... 9, then you can use the function parameter to save the 0....9 in a different way (actually using the closure)

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

SetTimeout ((function (i){

return function () {

Console.log (i);

}

}) (i), 0);

}

Javascript setTimeout (0), closures