在下一个操作之前等待几秒钟 - Javascript

Question

As commented in the code , I need a wait before checking the else if after writeFile(lFileData); . How to achieve this?

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

            if(i <= 1)
            {

                writeFile(lFileData); //This action takes a lot of time with its call backs. I need a wait here. 

            }

            else if(i > 1 && i <=3)
            {
                     someOtherfun()

            }

Answer 1

if(i <= 1){
    writeFile(lFileData); 
    doAdelay();
};

and:

function doAdelay(){
    setTimeout(function(){return true;},30000);
};

Hope this helps

Answer 2

您可以在elseif函数中使用set interval

setTimeout(function,3000);

Answer 3

So that means the writeFile function is asynchronous?

I would create a callback function in the writeFile function itself and then do the someOtherfun().

Edit : Due to you can not really do the rest of the iteration in the callback function (which you just said) you can do something like this:

function writeFile () {
    ... here goes your function ...
    if ( finished ) {
        window.finished = true;
    }
}

for (yourForCondition) {
    if () {
        window.finished = false;
        writeFile(); 
        while (!window.finished) {}
    }

    if () {
        someOtherFun();
    }
}

It's a bit dirty, but it should work. It would loop until writeFile() says he is done.

Edit2 : Will probably not work since "while (!window.finished) {} is a busy-wait loop that will peg one core to 100% and probably make the browser ask the user if the script should be killed. – Frédéric Hamidi "

Answer 4

You may want to rewrite the code to have the portion you want to run on a delay in its own function. From there call that function by calling performFunctionXAfterDelay() :

function performFunctionXAfterDelay() {
  // 1000 ms delay
  window.setTimeout(functionX,1000)

}

function functionX() {
   // YOUR TIME DELAYED CODE
}

Answer 5

var t = setInterval("javascript expression", milliseconds);

clearInterval(t);

u can use setInterval

Answer 6

hi i think there is no need of wait before execution of "else if(i > 1 && i <=3)" code. because if "if(i <= 1)" condition is true and " writeFile(lFileData); " gets executed, control will no be given for "else" part and " someOtherfun()" will not get executed. :)