CODEWITHSUNDEEP
javascript
ram
ram

Reputation: 37

for loop delay in javascript

How to set delay in for loop execution 

for(i=0; i<=10;i++){
        var s=i;//This line should execute for every 2 secs only
        }

How to give loop delay in java script....

I dont want like below..I want without using setTimeout...

for(i=0; i<=10;i++){
        setTimeout("setvalue()",2000); //This alert should display for every 2 secs only
        }

        function setvalue()
        {
         var s=i;
        }

please help me...

Upvotes: 1

Views: 7026

Answers (4)

veeTrain
veeTrain

Reputation: 2915

As others have stated, setTimeout can be used very well to handle these sorts of scenarios and setInterval could also be used but is discouraged by some.

You can even recursively call a function that has setTimeout built into it as mentioned in the MDN documentation of setInterval. The heading there mentions 'dangerous usage' but their solution to the danger is the block of code beneath.

There it mentions that to have a loop executing every x seconds (or milliseconds) then you can do the following and know for sure that the functions will only be executing one at a time and in-sequence:

(function loop(){
    setTimeout(function(){
        // logic here

        // recurse
        loop();

    }, 1000); // repeat loop 1 second after this branch has completed
})();

And if you want it to only do that a limited number of times, then you can create a variable outside of the loop and only recursively execute if the count is smaller than the number of times you want to execute for. Such as this:

var count = 0;
(function loop() {
    setTimeout(function() {
        // logic
        count++;
        if (count < 10) {
            loop();
        }
    }, 1000);
})();

Upvotes: 1

Madara&#39;s Ghost
Madara&#39;s Ghost

Reputation: 174957

Using setTimeout is inevitable, however, a recursive function might be a better solution for this one:

var i=0;
function recurs() {
    i = s;
    i++;
    if (i <= 10) recurs();
}

recurs();

Upvotes: 2

valderman
valderman

Reputation: 8745

You can't. JS runs in a single thread and any attempt to delay that thread will freeze the entire page. Using setTimeout is your only option.

EDIT: or setInterval; either way, there is no non-hairy way to express "halt execution here for x milliseconds."

Upvotes: 3

Jakub Konecki
Jakub Konecki

Reputation: 46008

Use setInterval()

var i = 0;

var interval = setInterval(function(){
    setValue();
    i += 1;

    if(i == 10)
        clearInterval(interval);
}, 2000);

There is no way to sleep for 2sec without freezing the whole browser. Javascript is single threaded.

Upvotes: 9

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