Javascript：无法停止setTimeout

Question

I'm working on a proxy server checker and have the following code to start the requests at intervals of roughly 5 seconds using the setTimeout function;

        function check() {

            var url = document.getElementById('url').value;
            var proxys = document.getElementById('proxys').value.replace(/\n/g,',');

            var proxys = proxys.split(",");

            for (proxy in proxys) {

                var proxytimeout = proxy*5000;

                t = setTimeout(doRequest, proxytimeout, url, proxys[proxy]);

            }
        }

However I can't stop them once their started!

        function stopcheck() {

            clearTimeout(t);

        }

A fix or better method will be more that appreciated.

Thank you Stack Overflow Community!

Answer 1

There are 2 major problems with your code:

1. t is overwritten for each timeout, losing the reference to the previous timeout each iteration.
2. t is may not be a global variable, thus stopcheck() might not be able to "see" t .

Updated functions:

function check() {
    var url         = document.getElementById('url').value;
    var proxys      = document.getElementById('proxys').value.replace(/\n/g,',');
    var timeouts    = [];
    var index;
    var proxytimeout;

    proxys = proxys.split(",");
    for (index = 0; index < proxys.length; ++index) {
        proxytimeout                = index * 5000;
        timeouts[timeouts.length]   = setTimeout(
            doRequest, proxytimeout, url, proxys[index];
        );
    }

    return timeouts;
}

function stopcheck(timeouts) {
    for (var i = 0; i < timeouts.length; i++) {        
        clearTimeout(timeouts[i]);
    }
}

Example of use:

var timeouts = check();

// do some other stuff...

stopcheck(timeouts);

Answer 2

Where is 't' being defined? It keeps being redefined in the for loop, so you will loose track of each timeout handle...

You could keep an array of handles:

var aTimeoutHandles = new Array();
var iCount = 0;
for (proxy in proxys) {

    var proxytimeout = proxy*5000;

    aTimeoutHandles[iCount++] = setTimeout(doRequest, proxytimeout, url, proxys[proxy]);

}

Answer 3

Define t outside of both functions first. Additionally, you're overwriting t with each iteration your for loop. Perhaps building a collection of references, and then to stop them you cycle through and clearTimeout on each.

Answer 4

You overwrite t each time you set the interval. Thus you only end up clearing the last one set.

Answer 5

You have a few problems there:

1. The main one is that you're overwriting t on each iteration of your for loop; you need an array of t s for your structure to work.
2. You're using for..in to loop through the indexes of the array. That's not what for..in is for (although there are a lot of people confused about that; see this article ). for..in loops through the property names of an object , not the indexes of an array , and therefore this usage breaks in non-trivial situations. Just use an old-fashioned for loop.
3. You're declaring proxys twice. This is actually harmless, but...
4. You're not declaring proxy at all (which isn't harmless; it becomes an implicit global).

I've updated the code in Jordan's excellent answer to address those.

Answer 6

Looks like you're setting multiple timeouts (one for each proxy), but trying to save them in the same variable. You probably need to use an array there, instead of a simple variable.