CODEWITHSUNDEEP
javascriptcss
Lord Farquaad
Lord Farquaad

Reputation: 707

CSS fade out multiple times


I'm making a website which will let you update an SQL table, and I want to add some sort of feedback when a button is clicked. I have made an invisible button (opacity=0) which lies to the right of each row as a status. I made this JS fade() function to set the opacity to 1, then slowly bring it back to 0, so a message pops up then fades away. 

 function fade () {
    var invis = document.getElementById("invis".concat(num.toString()));
        if(invis.style.opacity > .990) {
            invis.style.opacity = (invis.style.opacity) - .001;
            setTimeout(fade, 50);
        } else if(invis.style.opacity > 0) {
            invis.style.opacity = (invis.style.opacity) - .05;
            setTimeout(fade, 50);
        }
    }

The trouble is, since webpages are single-threaded, any other action will interrupt the animation and leave behind a half-faded status. So that's no good. So now I am trying to set up the invisible buttons to change class when a new row is updated. The new class looks like this: 

.invisible_anim {
    ...
    opacity: 0;
    animation:trans 3000ms;
}
@keyframes trans {
    0% {
       opacity: 1;
    } 
    50% {
        opacity: 1;
    }

This works fine, except it only works once. From here I cannot get the animation to play a second time. I have tried changing the class back to "invisible" then "invisible_anim" with no luck. I also can't use JQuery or Webkit. I'm wondering if there's some flag you can set for a button without actually clicking on it so I can reset the class when I need to? Or even some way to thread my JS function so I can stick with that.

Upvotes: 1

Views: 1196

Answers (3)

George F
George F

Reputation: 76

Have you considered using the CSS property "transition"? JavaScript has an event listener called "transitionend" that can trigger when your transition has ended, which you can use to reset the button.

First set the area for your alert button with the id invis.

CSS:

#invis {    
    opacity: 1;
    transition: opacity 3s;
}

Then in JavaScript, generate your button and its content, which will appear at opacity 1, then transition to opacity 0. Your addEventListener will trigger when the animation is done, remove the button and reset the opacity for the next trigger.

JavaScript:

var invis = getElementByID("invis");

function fade() {
    var button = document.createElement("button");
    invis.appendChild(button);
    invis.style.opacity = ("0");

    invis.addEventListener("transitionend", function(){
        invis.removeChild(button);
        invis.style.opacity = ("1");
    });
}

You can add the fade() function to your EventListener for the user "click."

This is my first time answering on StackOverflow, I hope this helps!

Upvotes: 1

Daemedeor
Daemedeor

Reputation: 1007

If you would like to play the animation multiple times (see docs here: https://developer.mozilla.org/en-US/docs/Web/CSS/animation), if you would like to play it twice only.

so this:

.invisible_anim {
...
opacity: 0;
animation:trans 3000ms;
}
@keyframes trans {
0% {
   opacity: 1;
} 
50% {
    opacity: 1;
}

would turn to

.invisible_anim {
...
opacity: 0;
animation:trans 3s 2 ;
}

@keyframes trans {
0% {
   opacity: 1;
} 
50% {
    opacity: 1;
}

EDIT: Apparently the requirements are different than what I thought. Instead the solution seems to be to key off the animation event located at https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Using_CSS_animations and then when that animation done do what you need to do: so in JS-only 

var e = document.getElementById("watchme");
e.addEventListener("animationend", listener, false);

function listener(){
   //do what you need to do here
}

Just be careful, the reason for this is that most browsers have different "animationend" events that fire at different times. So definitely will need to be tested in different browsers to make sure that the animation event is firing at the right time. There's a post at (https://css-tricks.com/controlling-css-animations-transitions-javascript/) that details some of the issues you might encounter.

Upvotes: 1

Blake A. Nichols
Blake A. Nichols

Reputation: 870

You need to start transparent then show then hide:

@keyframes trans {
    0% {
       opacity: 0;
    } 
    50% {
        opacity: 1;
    }
    100% {
        opacity: 0;
    }
}

Then simply add your class (remove after the 3000ms time period)

Upvotes: 0

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