How to run a function that calls a function finished it first before calling next function. Creating a callback function

Question

When a user click on any of the images all images (images_holder) slowly fade out. Then after its gone, another image fade in, then after 3 seconds that images fades out. After that its gone the images_holder fade-in again. The problem of mine is that before the fader is complete, the secondStep function is already running.

What I want is finish first first step with fader function complete then after that second step will run. Been trying to create this callback but no luck.

Here is my html

<div id="container">
    <!--<img src="images/background.jpg"/>-->
    <div id="faces_holder">
        <img id="face1" onclick="loadUnload(1)" src="images/face_03.png" width=350; height=656;/><img id="face2" onclick="loadUnload(2)" src="images/face_04.png" width=350; height=656;/><img id="face3" onclick="loadUnload(3)" src="images/face_05.png" width=350; height=656;/><img id="face4" onclick="loadUnload(4)" src="images/face_06.png" width=350; height=656;/><img id="face5" onclick="loadUnload(5)" src="images/face_07.png" width=350; height=656;/>
    </div>
    <div id="pop_face"><img id="popface_img" src=""/></div>
</div>

And here is my JavaScript:

    var id = "";
    var kindface=0;
    var fadeIn;
    var counterValue;
    var objHolder;


    function loadUnload(kindface){
        //FADEIN FADEOUT    
        function fader() {
            if(fadeIn == true){
                counterValue++;
                //setPoint = 9;
            }else{
                counterValue--;  // update parameters
                //console.log("hit");
            }
            objHolder.style.opacity = "0."+counterValue // show frame
            if (counterValue == setPoint){  // check finish condition
                clearInterval(id);
                console.log("end fader");
            }
        }

        //FADEOUT

Update

I just added this third step, how am I going to implement this? I want this third step run after secondStep finish the fader function?

function thirdstep() {
        console.log("begin second step: ")

            fadeIn = true;
            counterValue = 0;
            setPoint = 9;
            objHolder = document.getElementById("popface_img");
            objHolder.src = "images/"+ kindface +".png";

            id = setInterval(fader, 100); // draw every 100ms
            console.log("end second step: ")
        }

        function secondStep() {
            console.log("begin second step: ")

            fadeIn = true;
            counterValue = 0;
            setPoint = 9;
            objHolder = document.getElementById("popface_img");
            objHolder.src = "images/"+ kindface +".png";

            id = setInterval(fader, 100); // draw every 100ms
            console.log("end second step: ")
        }

        function firstStep(callback) {
            console.log("begin first step: ")

            fadeIn = false;
            objHolder = document.getElementById("faces_holder");
            counterValue = 10;
            setPoint = 0;


            id = setInterval(callback, 100); // draw every 100ms
            console.log("end first step: ")
            secondStep();

        }


        //RUN FIRST STEP FUNCTION 
        console.log("BEGIN process ")             
            firstStep(fader);

        console.log("END OF ALL process ")

    }

</script>

Answer 1

In your code:

> id = setInterval(callback, 100); // draw every 100ms
> console.log("end first step: ")
> secondStep();

secondStep is called immediately, it doesn't wait for the sequence established by setInterval to finish. You need to call secondStep from fader , eg

function loadUnload(kindface){

    [...]
    function fader() {

        if (counterValue == setPoint){  // check finish condition
            clearInterval(id);
            console.log("end fader");

            // now call secondStep
            secondStep();
        }
    }
    [...]
}