如何在for循环中为文本设置动画？

Question

I'm trying to create a sidebar animation effect as:

<div class="sidebar-description sidebar-personal-info-section">
    A passionate
    <span class="changing-keywords" id="change">
        <strong>
            <b class="hidden">software engineer</b>
            <b class="hidden">lifelong learner</b>
            <b class="hidden">blogger</b>
            <b class="hidden">traveller</b>
        </strong>
    </span><br>
</div>

I've written the HTML code but issue is that how should I display each text one at a time with small delay with slide-out animation effect? The loop should work infinite times.

Answer 1

Make it simple by using CSS key-frame animation.

Below is an example.

 body{ font-family:calibri; } .codinfox-changing-keywords{ vertical-align:top; overflow:hidden; height:20px; position:relative; display: inline-block; width: 250px; } .hidden{ position:absolute; top: 20px; display:inline-block; width:250px; opacity:0; animation: slideme 8s infinite; } .hidden:nth-child(3){ animation-delay: 2s; } .hidden:nth-child(5){ animation-delay: 4s; } .hidden:nth-child(7){ animation-delay: 6s; } @keyframes slideme { 0% { top: 20px; opacity:0; } 5% { top: 0px; opacity:1; } 10%{ top : 0; opacity:1; } 20%{ opacity:1; } 25% { opacity:0.1; top : 0; } 30% { opacity:0; top: 20px; } } 

 <div class="codinfox-sidebar-description sidebar-personal-info-section"> A passionate <div class="codinfox-changing-keywords" id="change"> <strong> <b class="hidden">software engineer</b><br/> <b class="hidden">lifelong learner</b><br/> <b class="hidden">blogger</b><br/> <b class="hidden">traveller</b> </strong> </div> </div> 

You can test it here as well!

Answer 2

First, you need to work a little bit on your HTML. The <strong> tag shouldn't be used to style elements, not to mention the <b> tags. Below is my version of the code. First the HTML:

<div class="codinfox-sidebar-description sidebar-personal-info-section">
    A passionate
    <span class="changing-keyword shown">software engineer</span>
    <span class="changing-keyword">lifelong learner</span>
    <span class="changing-keyword">blogger</span>
    <span class="changing-keyword">traveller</span>
</div>

I took the liberity to change the class names and remove some tags that were, in my opinion, unnecessary here. Now, JavaScript:

const changingKeywords = document.querySelectorAll('span.changing-keyword');
const keywordsToggle = setKeywordsToggle(changingKeywords);

function setKeywordsToggle (keywords) {
    let index = 0;
  return setInterval(() => {
    keywords[index].classList.remove('shown');
    if (++index >= keywords.length) 
        index = 0;
    keywords[index].classList.add('shown');
  }, 2000);
}

Notice that I actually return the setInterval() function and assign it to keywordsToggle variable. This way, if I ever want to stop the animation, I can easily do so by running clearInterval() . The code toggles through all keywords it finds and assigns the shown class to the element determined by the value of index variable.

Finally, sample CSS:

.sidebar-personal-info-section {
  position: relative;
}

.changing-keyword {
  font-weight: bold;
  opacity: 0;
  transition: opacity 1s, visibility 1s;
  visibility: collapse;
  position: absolute;
  padding-left: .2rem;
}

.shown {
  opacity: 1;
  visibility: visible;
}

Notice the visibility transition, which actually works as transition delay. Other than that, I had to use a position property to make sure that every keyword is positioned near the "passionate" word, otherwise every word would appear in it's original position (I didn't use display:none since it's not animatable).

Working example:

 const changingKeywords = document.querySelectorAll('span.changing-keyword'); const keywordsToggle = setKeywordsToggle(changingKeywords); function setKeywordsToggle (keywords) { let index = 0; return setInterval(() => { keywords[index].classList.remove('shown'); if (++index >= keywords.length) index = 0; keywords[index].classList.add('shown'); }, 2000); } 

 .sidebar-personal-info-section { position: relative; } .changing-keyword { font-weight: bold; opacity: 0; transition: opacity 1s, visibility 1s; visibility: collapse; position: absolute; padding-left: .2rem; } .shown { opacity: 1; visibility: visible; } 

 <div class="codinfox-sidebar-description sidebar-personal-info-section"> A passionate <span class="changing-keyword shown">software engineer</span> <span class="changing-keyword">lifelong learner</span> <span class="changing-keyword">blogger</span> <span class="changing-keyword">traveller</span> </div> 

Answer 3

My quick and dirty would look something like this.

// add rotate to Array
Array.prototype.rotate = function(n) {
    return this.slice(n, this.length).concat(this.slice(0, n));
}

// setup array
const jobs = ['employee', 'manager'];

// rotate jobs function
const rotateJobs = () => {
    document.querySelector('#id').innerHtml = jobs.rotate(1).shift();
}

// set interval
setInterval(rotateJobs, 1000);

The fade in / slide animation should be handled in css transitions.

Answer 4

This something what I finally figured out!

var title = ['software engineer', 'tech blogger', 'traveller', 'lifelong learner'];

var i = 0;  // the index of the current item to show

setInterval(function() {            // setInterval makes it run repeatedly
  document
    .getElementById('change')
    .innerHTML = title[i++];    // get the item and increment
  if (i == title.length) i = 0;   // reset to first element if you've reached the end
}, 2000);