在Javascript中定时循环

Question

I don't even know how to get started with this: I need a for loop that executes a function (say a simple console.log() ) with a timed delay between each execution. I've been trying to do it with setTimeout() and it never works. If I call the function that has the loop from setTimeout, it won't work. Ideally I'd want my for loop to print something x times, with a couple of seconds delay between each printing. Any ideas how that might work? I've tried something like this:

function printStuff(){
for(var i=0;i<5;i++){
console.log(i);
}
};
setTimeout(printStuff(),1000);

Answer 1

For me you should execute setInterval and inside this you should increase counter. When counter reach the limit you simply clear interval.

var counter = 0;
var limit = 10;
var myVar = setInterval(function(){ 
    if (counter > limit)
    {
        clearInterval(myVar);
    }
    counter++;
    console.log("test"); 
}, 1000);

Answer 2

init();

function init() {
  setTimeout(init, 2*1000); // wait 2 sec then call init again

  console.log(Date());
}

Or use setInterval :

// Call init after 2 sec and repeat calling it every 2. sec
setInterval(init, 2*1000);

function init() {
  console.log(Date());
}

Answer 3

You could use the async module.

var count = 0;
async.whilst(
    function () { return count < 5; },
    function (callback) {
        count++;
        console.log(count);
        setTimeout(callback, 1000);
    },
    function (err) {
        // 5 seconds have passed
    }
); 

This way the count will be printed every second

Answer 4

var i = 0;
function timeout(){
    setTimeout(log, 1000);
} 
function log(){
    console.log(i++);
    timeout();
}
log();

http://jsfiddle.net/sq4v0kbf/

Answer 5

Use setInterval() instead of setTimeout() . Parameters are just the same:

setInterval(function () {
  // your utility code goes here
}, 2000);

Answer 6

Here is one more way to do it. Use a wrapper function.

var time = 2000;
for (var i = 0; i < 10; i++) {
    (function (i) {
        setTimeout(function () {
            console.log(i);
        }, time);
    })(i);
    time+=2000;

}

Answer 7

You can create a sort of delayed loop function with the number of iterations/times you want to run. Something like this:

var delayedLoop = function (n, milliseconds) {                                       
    var iteration = function (n) {                                              
        if (n > 0) {
            n--;
            console.log(n);                                             
            setTimeout(function () {                                               
                iteration(n)                                                          
            }, milliseconds);                                                              
        }                                                                        
    };                                                                         
    iteration(n);                                                               
}
delayedLoop(4, 1000);

You could even expand the idea and even passing a function to be executed each time.

See demo .

Answer 8

Here's what I think is simpler ( and doesn't have the fallbacks of ) than a setInterval

  var limit = 10, counter = 0, delay = 1000; function doIt() { document.body.innerHTML += 'Hit counter: ' + (counter++) + '<br />'; if (counter < limit) { setTimeout(doIt, delay); } } doIt(); 

And you can generalize it

 function runTimedLoop(delay, howMany, callback) { var index = 0; function iteration() { callback(index++); if (index < howMany) { setTimeout(iteration, delay); } } iteration(); } runTimedLoop(1000, 10, function(index) { document.body.innerHTML += 'Hit counter: ' + (index++) + '<br />'; });