javascript - recursive function & setTimeout_问答_开发者

javascript - recursive function & setTimeout

开发者 https://www.devze.com 2023-04-01 14:09 出处：网络

I am trying to write a javascript function that when called performs function DoSomething() once, but can be triggered to perform the function repeatedly until triggered to stop.

I am using setTimeout() function. I am not sure if this is best method from performance and memory point of view. Also I would like to avoid global variable if possible

<!DOCTYPE html>
<html>
    <script src="jquery.js"></script>

    <script>
    var globalCheckInventory = false;

    $(document).ready(function(){
        // start checking inventory
        globalCheckInventory = true;                 
        myTimerFunction();  
    }); 

    // check inventory at regular intervals, until condition is met in DoSomethi开发者_开发百科ng
    function myTimerFunction(){
        DoSomething();
        if (globalCheckInventory == true)
        {
            setTimeout(myTimerFunction, 5000);      
        }           
    }

    // when condition is met stop checking inventory
    function DoSomething() {     
        alert("got here 1 ");
        var condition = 1;
        var state = 2 ;
        if (condition == state)
        {
            globalCheckInventory = false;
        }        
    }
    </script>

This is probably the easier way to do what you're describing:

$(function () {
  var myChecker = setInterval(function () {
    if (breakCondition) {
      clearInterval(myChecker);
    } else {
      doSomething();
    }
  }, 500);
});

Another way to do it would be the store the timer ID and use setInterval and clearInterval

var timer = setInterval(DoSomething);

function DoSomething() {
    if (condition)
        clearInterval(timer);
}

I see nothing wrong with your implementation other than the pollution of the global namespace. You can use a closure (self-executing function) to limit the scope of your variables like this:

(function(){

  var checkInventory = false, inventoryTimer;

  function myTimerFunction() { /* ... */ }

  function doSomething() { /* ... */ }

  $(document).ready(function(){
    checkInventory = true;
    /* save handle to timer so you can cancel or reset the timer if necessary */
    inventoryTimer = setTimeout(myTimerFunction, 5000);
  });

})();

Encapsulate it:

function caller(delegate, persist){
    delegate();
    if(persist){
        var timer = setInterval(delegate, 300);
        return {
            kill: function(){
                clearInterval(timer);
            }
        } 
    }   
}
var foo = function(){
    console.log('foo');
}

var _caller = caller(foo, true);
//to stop: _caller.kill()