第五天來到，這次做的是網站上經常看見的視覺效果，主要是利用css transform跟transition搭配，少少的js就能做到！

Day5

照慣例先上Demo，這次在畫面上製作五個區塊，點擊之後會有放大跟文字跑出的效果，接著來看看code吧
html:先做一個class為panels的div區塊，將五個panel區塊包進去，並且放上文字

<div class="panels">
    <div class="panel panel1">
      <p>Hey</p>
      <p>Let's</p>
      <p>Dance</p>
    </div>
    <div class="panel panel2">
      <p>Give</p>
      <p>Take</p>
      <p>Receive</p>
    </div>
    <div class="panel panel3">
      <p>Experience</p>
      <p>It</p>
      <p>Today</p>
    </div>
    <div class="panel panel4">
      <p>Give</p>
      <p>All</p>
      <p>You can</p>
    </div>
    <div class="panel panel5">
      <p>Life</p>
      <p>In</p>
      <p>Motion</p>
    </div>
  </div>

css:css部分主要使用flex排版，以及底下這一段code，一開始設定文字translateY，讓他們看不到，點擊後增加open-active這個class來改變translateY而達到文字出現的效果

.panel > *:first-child { transform: translateY(-100%); }
.panel.open-active > *:first-child { transform: translateY(0); }
.panel > *:last-child { transform: translateY(100%); }
.panel.open-active > *:last-child { transform: translateY(0); }

完整的css code:

html {
  box-sizing: border-box;
  background: #ffc600;
  font-family: 'helvetica neue';
  font-size: 20px;
  font-weight: 200;
}

body {
  margin: 0;
}

*, *:before, *:after {
  box-sizing: inherit;
}
.panels {
  min-height: 100vh;
  overflow: hidden;
  display: flex;
}
.panel {
  background: #6B0F9C;
  box-shadow: inset 0 0 0 5px rgba(255,255,255,0.1);
  color: white;
  text-align: center;
  align-items: center;
  /* Safari transitionend event.propertyName === flex */
  /* Chrome + FF transitionend event.propertyName === flex-grow */
  transition:
    font-size 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
    flex 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
    background 0.2s;
  font-size: 20px;
  background-size: cover;
  background-position: center;
  flex: 1;
  justify-content: center;
  display: flex;
  flex-direction: column;
}
.panel1 { background-image:url(https://source.unsplash.com/gYl-UtwNg_I/1500x1500); }
.panel2 { background-image:url(https://source.unsplash.com/rFKUFzjPYiQ/1500x1500); }
.panel3 { background-image:url(https://images.unsplash.com/photo-1465188162913-8fb5709d6d57?ixlib=rb-0.3.5&q=80&fm=jpg&crop=faces&cs=tinysrgb&w=1500&h=1500&fit=crop&s=967e8a713a4e395260793fc8c802901d); }
.panel4 { background-image:url(https://source.unsplash.com/ITjiVXcwVng/1500x1500); }
.panel5 { background-image:url(https://source.unsplash.com/3MNzGlQM7qs/1500x1500); }
/* Flex Items */
.panel > * {
  margin: 0;
  width: 100%;
  transition: transform 0.5s;
  flex: 1 0 auto;
  display: flex;
  justify-content: center;
  align-items: center;
}
.panel > *:first-child { transform: translateY(-100%); }
.panel.open-active > *:first-child { transform: translateY(0); }
.panel > *:last-child { transform: translateY(100%); }
.panel.open-active > *:last-child { transform: translateY(0); }
.panel p {
  text-transform: uppercase;
  font-family: 'Amatic SC', cursive;
  text-shadow: 0 0 4px rgba(0, 0, 0, 0.72), 0 0 14px rgba(0, 0, 0, 0.45);
  font-size: 2em;
}

.panel p:nth-child(2) {
  font-size: 4em;
}
.panel.open {
  flex: 5;
  font-size: 40px;
}

js:js部分主要做監聽點擊事件，以及transitioned的事件來觸發toggle class的動作

//選取所有class名為panel的元素
    const panels = document.querySelectorAll('.panel');
    //panel點擊後增加open這個class名，如果已經有了則拿掉
    function toggleOpen() {
      this.classList.toggle('open');
    }
    //toggleActive主要在transition結束後呼叫，這時e.propertyName會有flex跟font-size
    //所以取其中一種，執行一次toggle class就好
    function toggleActive(e) {
      if (e.propertyName.includes('flex')) {
        this.classList.toggle('open-active');
      }
    }
    //將每個panel綁定點擊以及transitioned事件
    panels.forEach(panel => panel.addEventListener('click', toggleOpen));
    panels.forEach(panel => panel.addEventListener('transitionend', toggleActive));

以上就是第五天的內容！