What is a best way to execute function until before call is finished?

Example JavaScript function:

var notifyState = function(state) {
setTimeout(function () {
  /*Do something*/
}, 2000);
};

Then I call function twice:

notifyState('State1');
notifyState('State2');

This functions executing in paraller. What best way to execute them sequentially? I can only modify notifyState function. notifyState can execute only with one parameter.

Update: Function notifyState informs what actual state is in flash game. It saves it in html code, when state change then state is override. In selenium test I downloading state from html code, but state change too fast that selenium not noticed this, so I tried sleep JavaScript.

What is a best way to execute function until before call is finished?

Example JavaScript function:

var notifyState = function(state) {
setTimeout(function () {
  /*Do something*/
}, 2000);
};

Then I call function twice:

notifyState('State1');
notifyState('State2');

This functions executing in paraller. What best way to execute them sequentially? I can only modify notifyState function. notifyState can execute only with one parameter.

Update: Function notifyState informs what actual state is in flash game. It saves it in html code, when state change then state is override. In selenium test I downloading state from html code, but state change too fast that selenium not noticed this, so I tried sleep JavaScript.

• javascript

• 9 time for Callback – Praveen Commented Jan 8, 2014 at 12:13
• First of all... there's no multithreading in javascript so your function will always be run sequentially but you can't tell in which order – SOReader Commented Jan 8, 2014 at 12:15
• @PraveenJeganathan: Callback isn't going to work if OP can only modify notifyState function – musefan Commented Jan 8, 2014 at 12:15
• 1 @oGeez - Yes, I can create helper function to call notifyState – estradowiec Commented Jan 8, 2014 at 12:20
• 1 @SOReader: there is multithreading in JavaScript, see web workers: developer.mozilla/en-US/docs/Web/Guide/Performance/… – simon Commented Jan 8, 2014 at 12:31

3 Answers 3

It depends on whether you want #notifyState to use setTimeout or not. If you don't need the setTimeout then you just re-write as follows:

var notifyState = function(state) {
  /* Do something */
}

notifyState('State 1');
notifyState('State 2');

If you want to keep the setTimeout and chain the calls, so that the second notify is executed after the first, you will have to provide a callback:

var notifyState = function(state, callback) {
  setTimeout(function() {
    /* Do something */
    if (callback) {
      callback();
    }
  }, 2000);
}

notifyState('State 1', function() {
  notifyState('State 2');
});

EDIT

Seems that the OP problem is different. My understanding is that your are providing #notifyState function as a callback to a 3rd party Flash that you don't control and you want to ensure that calls to notifyState execute in the same order and one after another, so you don't have 2 parallels calls to notifyState running at the same time. To achieve this you will need to introduce a queue that will keep the states and change the notifyState function in a way to execute only one state at the time. I will assume your need for the setTimeout is important here and keep it that way. See the code below:

var Queue = [],
    running = false;
var notifyState = function(state) {
  if (running) {
    Queue.push(state);
  } else {
    running = true;
    setTimeout(function() {
      /* Do something */
      running = false;
      var nextState = Queue.pop();
      if (nextState) {
        notifyState(nextState);
      }
    }, 2000);
  }
}

Add an optional parameter that will act as a callback function. Check that the parameter is in fact a function, if it is, run it.

var notifyState = function(state,fn) {
    setTimeout(function () {
      /*DoSomething*/
      if(typeof(fn)=='function'){ fn(); }
    }, 2000);
};

You can then call the functions like so:

notifyState('State1', function(){
    notifyState('State2');
});

JSFiddle

var notifyState = function(state, callback) {
    setTimeout(function () {

    /*Do something*/

    callback();

    }, 2000);
};

Calling function:

var state1CompleteHandler = function() {
    // code to execute when state 1 logic pletes
    notifyState('State2');
}
notifyState('State1', state1CompleteHandler);