# 實作 Loader ( 先記錄，待理解 css 動畫部分 )
###### tags: `實作 Style`

## 結果

---

## 概念
* 有一個整個畫面的 div => custom-preloader
* custom-preloader 畫面中有 轉圈圈效果
* 放在 _Layout 給全域 (View) 呼叫

---

## 目前用法
* 在 a 標籤的 onclick 事件呼叫 showLoader()，就可以達到讀取的效果，跳轉後就會消失
* ajax 時呼叫

---

## HTML

<div id="custom-preloader" class="d-none">
    <div id="loader"></div>
</div>

---

## Scirpt

var showLoader = function () {
    $("#custom-preloader").attr("style", "display: block !important");
};

var hideLoader = function () {
    $("#custom-preloader").attr("style", "display: none !important");
}

---

## Style

#custom-preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #3b3f442e;
    z-index: 1050;
}

#loader {
    display: block;
    position: relative;
    left: 50%;
    top: 50%;
    width: 150px;
    height: 150px;
    margin: -75px 0 0 -75px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #9370DB;
    -webkit-animation: spin 2s linear infinite;
    animation: spin 2s linear infinite;
}

#loader:before {
    content: "";
    position: absolute;
    top: 5px;
    left: 5px;
    right: 5px;
    bottom: 5px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #BA55D3;
    -webkit-animation: spin 3s linear infinite;
    animation: spin 3s linear infinite;
}

#loader:after {
    content: "";
    position: absolute;
    top: 15px;
    left: 15px;
    right: 15px;
    bottom: 15px;
    border-radius: 50%;
    border: 3px solid transparent;
    border-top-color: #FF00FF;
    -webkit-animation: spin 1.5s linear infinite;
    animation: spin 1.5s linear infinite;
}

@-webkit-keyframes spin {
    0% {
        -webkit-transform: rotate(0deg);
        -ms-transform: rotate(0deg);
        transform: rotate(0deg);
    }

    100% {
        -webkit-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        transform: rotate(360deg);
    }
}

@keyframes spin {
    0% {
        -webkit-transform: rotate(0deg);
        -ms-transform: rotate(0deg);
        transform: rotate(0deg);
    }

    100% {
        -webkit-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        transform: rotate(360deg);
    }
}

[來源-Bootstrap Snippet-preloader by Shakibur22](https://bootsnipp.com/snippets/dlAQB)