Introduction to three ways to implement text ticker (code examples)

What this article brings to you is an introduction to three ways to implement text marquees (code examples). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

I recently wrote a project requirement for a text marquee. I just started writing it in js and was able to complete the requirement. Later, I thought about using another method (html and css respectively) to achieve the same requirement to reduce performance consumption.

First, demand analysis:

Requirement point 1. Determine the length of the text and the length of the container. If the length of the text is greater than the length of the container, start scrolling, otherwise it will not scroll;

Demand point 2. Determine the end of scrolling and trigger events at the end time (for example: adding or subtracting styles, etc.);

1. JS implementation

Thinking :

1. Determine the length of the text and the length of the container. If the length of the text is greater than the length of the container, start scrolling, otherwise it will not scroll. (offsetWidth)

2. Get the distance from the scroll bar to the left side of the element, and scroll recursively until the scrolled distance is equal to the length of the text and exit the recursion. (scrollLeft)

Rendering

Note: The text jitter phenomenon is due to the long recording time, and the GIF file produced by PS can only be 500 frames Below, text jitter appears by lowering the frame rate.

Code part

HTML：

<div class="box">
    <div class="content">
        <p class="text">1.文字如果超出了宽度自动向左滚动文字如果超出了宽度自动向左滚动。</p>
    </div>
</div>

CSS：

*{
  margin:0;
  padding:0;
}
.box{
  margin-left: 200px;
  margin-top: 100px;
  color: #FFF;
  white-space: nowrap;
  overflow: hidden;
  width: 300px;
  background: #000;
}
.content p{
  display:inline-block;
}
.content p.padding{
  padding-right: 300px;
}

JS：

let [box, content, text] = [
  document.querySelector('.box'),
  document.querySelector('.content'),
  document.querySelector('.text')
]
let [textWidth, boxWidth] = [
  text.offsetWidth,
  box.offsetWidth
]
window.onload=function checkScrollLeft(){
  // 判断文字长度是否大于盒子长度
  if(boxWidth > textWidth){ return false}
  content.innerHTML += content.innerHTML
  document.querySelector('.text').classList.add('padding')
  // 更新
  textWidth = document.querySelector('.text').offsetWidth
  toScrollLeft()
}
function toScrollLeft(){
  //  如果文字长度大于滚动条距离，则递归拖动
  if(textWidth > box.scrollLeft){
    box.scrollLeft++
    setTimeout('toScrollLeft()', 18);
  }
  else{
    // setTimeout("fun2()",2000);
  }
}

Summary

The js method can perfectly satisfy sub-need point 1 and self-need point 2.

The length of text and container can be judged by offsetWidth. If the text is longer than the container, scrolling begins.

window.onload=function checkScrollLeft(){
  // 判断文字长度是否大于盒子长度
  if(boxWidth >= textWidth){ return false}
  content.innerHTML += content.innerHTML
  document.querySelector('.text').classList.add('padding')
  // 更新
  textWidth = document.querySelector('.text').offsetWidth
  // 开始滚动  触发事件
  toScrollLeft()
}

Judge the end of scrolling based on the distance from the scroll bar to the left side of the element and the length of the text. If the distance from the scroll bar to the left side of the element is equal to the length of the text, the scrolling will end.

function toScrollLeft(){
  //  如果文字长度大于滚动条距离，则递归拖动
  if(textWidth > box.scrollLeft){
    box.scrollLeft++
    setTimeout('toScrollLeft()', 18);
  }
  else{
    // 滚动结束 触发事件
  }
}

2. HTML implementation

Rendering:

Code part:

  <marquee>1.文字如果超出了宽度自动向左滚动文字如果超出了宽度自动向左滚动。</marquee>

Very concise code~,~

marquee’s API

##Although the API of the marquee tag is very rich, the tag is not available on MDN Described like this:

This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

elements It is obsolete, please do not use it anymore. Although some browsers still support it, it's not required. Also, using this element is basically one of the worst things you can do to your users, so please don't do it.

Therefore, according to the principle of closely following document standards in our IT circle, we please try not to use the marquee tag in our projects

3. CSS implementation

Rendering

Code part

HTML：

<div class="wrap">
  <div class="cont">
    <p class="txt">1.文字如果超出了宽度自动向左滚动文字如果超出了宽度自动向左滚动。</p>
    <p class="txt">1.文字如果超出了宽度自动向左滚动文字如果超出了宽度自动向左滚动。</p>        
  </div>
</div>

CSS：

*{
  padding: 0; 
  margin: 0; 
  box-sizing: border-box;
}
.wrap{ 
  margin:10% auto; 
  background: #ddd; 
  font-size: 0; 
  /* 固宽，溢出隐藏 */
  width: 300px; 
  height: 40px; 
  overflow: hidden;
  white-space: nowrap;
  /* 相对定位 */
  position: relative;
}
.wrap  .cont{
  position: absolute; 
  top: 0;
  left: 0; 
  height: 100%;
  /* 关键 */
  width: 200%;
  transition:left 10s linear;
}
.wrap .txt{ 
  display: inline-block; 
  font-size: 18px;
  line-height: 30px; 
  margin-top: 5px; 
  color: #fff;
  background: #000;
}

JS:

var cont = document.querySelector('.cont')
var wrap = document.querySelector('.wrap')
var text = document.querySelector('.txt')
var wrapWidth = wrap.offsetWidth
var textWidth = text.offsetWidth
window.onload=function checkScrollLeft(){
  // 判断文字长度是否大于盒子长度  开始滚动
  if(textWidth > wrapWidth) {
    text.style.paddingRight = '300px'
    cont.style.left = "-870px"
  }
  // 滚动结束
  document.addEventListener("transitionend", function (){
    console.log("end")
  }, false)
}

Summary

CSS can meet sub-need point 1 and can determine when to start scrolling.

window.onload=function checkScrollLeft(){
  // 判断文字长度是否大于盒子长度
  if(textWidth > wrapWidth) {
    // 开始滚动  触发事件
    text.style.paddingRight = '300px'
    cont.style.left = "-870px"
  }
}

At the same time, it can also meet sub-demand point 2 and determine the end of scrolling.

// 滚动结束
document.addEventListener("transitionend", function (){
    console.log("end")
}, false)

Conclusion

Review of requirements

Requirement point 1. Determine the length of the text and the length of the container. If the text length is greater than the container length, start scrolling , otherwise it will not scroll;

Requirement point 2. Determine the end of scrolling and trigger events at the end time (for example: adding or subtracting styles, etc.);

Comparison of the advantages and disadvantages of implementation methods

js realizes the marquee effecthtml realizes the marquee effectcss realizes the marquee effect EffectDemand point 1✔️✘✔️Requirement point 2✔️✘✔️Compatibility✔️ ✘✘If you need to meet the requirements, both js and css can be implemented. However, considering compatibility, CSS is not supported below ios9 and below Android 4.4. Other good solutions are under consideration. If you have a good solution, please leave a message below to communicate with me~

In addition, CSS can still be given priority if it is used for pure display effects, such as the CSS seamless scrolling below

Rendering

Code part

HTML：

<div class="wrap">
  <div class="cont">
    <p class="txt">1.文字如果超出了宽度自动向左滚动文字如果超出了宽度自动向左滚动。</p>
    <p class="txt">2.文字如果超出了宽度自动向左滚动文字如果超出了宽度自动向左滚动。</p>
  </div>
</div>

CSS：

*{
  padding: 0; 
  margin: 0; 
  box-sizing: border-box;
}
.wrap{ 
  position: relative; 
  width: 40%; 
  height: 40px; 
  margin:10% auto; 
  background: #ddd; 
  font-size: 0; 
  overflow: hidden;
}
.wrap  .cont{
  position: absolute; 
  top: 0; 
  left: 0;
  /* 宽度 大于容器的两倍即可 */
  width: 200%; 
  -webkit-animation:5s move infinite linear;
}
.wrap .txt{ 
  font-size: 18px; 
  color: #fff;
  display: inline-block; 
  /* 宽度 等于容器的宽度 */
  width: 50%; 
  height: 30px; 
  border-left:1px solid #fff; 
  line-height: 30px; 
  text-align: center; 
  margin-top: 5px; 
  background: #000;
}
.wrap:hover .cont{ 
  -webkit-animation-play-state:paused;
}

@-webkit-keyframes move{
  /* 原理 left值的变化 移动一个容器的宽度 */
  0%{
    left: 0;
  }
  100%{
    left: -100%;
  }
}

So, the tool itself has no advantages Which tool should be used when? We need to have clear ideas.

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