JS30 day05 - Flex Panels Image Gallery

作業內容

今天要做的是做出一個網頁，畫面上有五條欄位，我點擊其中一個他就會放大，並同時會有字從上方跟下方冒出來，再點一次他就會縮小可以參考這份 CodePen

學到什麼

列點如下：

CSS
1. box-shadow 內陰影的效果還滿漂亮的 box-shadow: inset 0 0 0 5px rgba(255,255,255,0.1); 參考資料：https://boohover.pixnet.net/blog/post/35116159-%E9%99%B0%E5%BD%B1%E6%95%88%E6%9E%9C%E5%8F%8A%E5%85%89%E6%9A%88%E6%95%88%E6%9E%9C%E7%9A%84-box-shadow-%28css-property%29
2. flex 的 flex-grow / flex-shrink / flex-basis 參考資料：https://cythilya.github.io/2017/04/06/flexbox-advance/
3. transition 裡面可以指定各種不同的動畫，表現時間跟方式
```
.panel {
  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;
}
```
JS
1. 使用 toggle 來新增或刪除 class ex. this.classList.toggle('open-active');
2. 其實單就 Chrome 瀏覽器來說，if(e.propertyName.includes("flex")) 這句可以改成：if(e.propertyName === "flex-grow")，重點在於 Safari 裡面這個事件叫做 flex 而不是 flex-group ，為了符合所有瀏覽器才這樣寫
3. 在這次的練習中，有一個很容易犯錯的點：我的 JS 其中有一行是這樣：
```
panels.forEach( panel => (panel.addEventListener('transitionend', toggleActive)));
```
如果我的 function 這樣寫：
```
function toggleActive(e){
  this.classList.toggle('open-active');
};
```
結果是： 什麼都沒發生

為什麼呢？因為這裡會監聽到兩個'transitinend'事件：flex-grow 跟 font-size，因此他會很快的加上這個 class 又很快的拔掉（觸發兩次），所以要選擇一個來監聽，在這次作業中選擇監聽 flex-grow 事件：
```
function toggleActive(e){
  if(e.propertyName.includes("flex")) {
    this.classList.toggle('open-active');
  }
};
```

總結

今天這個效果滿炫的，我喜歡！然後又再次體會到自己前端能力的不足，再接再厲！

參考資料： https://github.com/wesbos/JavaScript30

code 內容： HTML:

<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:

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 {
  flex: 1;
  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;
  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 Children */
.panel > * {
  flex: 1;
  margin: 0;
  width: 100%;
  transition: transform 0.5s;
  display: flex;
  justify-content: center;
  align-items: center; 
  /* border: 1px solid red; */
}
.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 {
  font-size: 40px;
  flex: 5;
}

JS:

const panels = document.querySelectorAll('.panel');

function toggleOpen(e){
  this.classList.toggle('open')
};

function toggleActive(e){
  if(e.propertyName.includes("flex")) {
    this.classList.toggle('open-active');
  }
};

panels.forEach( panel => (panel.addEventListener('click', toggleOpen)));
panels.forEach( panel => (panel.addEventListener('transitionend', toggleActive)));