写CSS的常用套路(用JS分割文本)

用JS分割文本

还有一种经常用到的玩法：用JS将句子或单词分割成字母，并给每个字母加上不同延时的动画，同样也很华丽。

HTML:

<p class="landIn">Ano hi watashitachi mada shiranai no Fushigi no monogatari desu.</p>

CSS:

@import url("https://fonts.googleapis.com/css?family=Lora:400,400i,700");

body {
  display: flex;
  flex-direction: column;
  height: 100vh;
  justify-content: center;
  align-items: center;
  background-image: linear-gradient(rgba(16, 16, 16, 0.8),
      rgba(16, 16, 16, 0.8)),
    url(https://i.loli.net/2019/10/18/buDT4YS6zUMfHst.jpg);
  background-size: cover;
}

p {
  margin: 0 9em;
  font-size: 2em;
  font-weight: 600;
}

.landIn {
  display: flex;
  flex-wrap: wrap;
  line-height: 1.8;
  color: white;
  font-family: Lora, serif;
  white-space: pre;

  span {
    animation: landIn 0.8s ease-out both;
  }
}

@keyframes landIn {
  from {
    opacity: 0;
    transform: translateY(-20%);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

JS:

let landInTexts = document.querySelectorAll(".landIn");
landInTexts.forEach(landInText => {
  let letters = landInText.textContent.split("");
  landInText.textContent = "";
  letters.forEach((letter, i) => {
    let span = document.createElement("span");
    span.textContent = letter;
    span.style.animationDelay = `${i * 0.05}s`;
    landInText.append(span);
  });
});

一般我们都是从第一个元素开始交错的。但如果要从中间元素开始交错的话，就要给当前元素的延时各加上一个值，这个值就是中间元素的下标到当前元素的下标的距离（也就是下标之差的绝对值）与步长的乘积，即：delay + Math.abs(i - middle) * step，其中中间元素的下标middle = letters.filter(e => e !== "").length / 2

HTML:

<div class="reveal">sword art online</div>

CSS:

@import url("https://fonts.googleapis.com/css?family=Raleway:400,400i,700");

body {
  display: flex;
  height: 100vh;
  justify-content: center;
  align-items: center;
  text-align: center;
  background: #222;
}

.reveal {
  position: relative;
  display: flex;
  color: #6ee1f5;
  font-size: 2em;
  font-family: Raleway, sans-serif;
  letter-spacing: 3px;
  text-transform: uppercase;
  white-space: pre;

  span {
    opacity: 0;
    transform: scale(0);
    animation: fadeIn 2.4s forwards;
  }

  &::before,
  &::after {
    position: absolute;
    content: "";
    top: 0;
    bottom: 0;
    width: 2px;
    height: 100%;
    background: white;
    opacity: 0;
    transform: scale(0);
  }

  &::before {
    left: 50%;
    animation: slideLeft 1.5s cubic-bezier(0.7, -0.6, 0.3, 1.5) forwards;
  }

  &::after {
    right: 50%;
    animation: slideRight 1.5s cubic-bezier(0.7, -0.6, 0.3, 1.5) forwards;
  }
}

@keyframes fadeIn {
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes slideLeft {
  to {
    left: -6%;
    opacity: 1;
    transform: scale(0.9);
  }
}

@keyframes slideRight {
  to {
    right: -6%;
    opacity: 1;
    transform: scale(0.9);
  }
}

JS:

let duration = 0.8;
let delay = 0.3;
let revealText = document.querySelector(".reveal");
let letters = revealText.textContent.split("");
revealText.textContent = "";
let middle = letters.filter(e => e !== " ").length / 2;
letters.forEach((letter, i) => {
  let span = document.createElement("span");
  span.textContent = letter;
  span.style.animationDelay = `${delay + Math.abs(i - middle) * 0.1}s`;
  revealText.append(span);
});