forked from theluyuan/Web
269 lines
5.1 KiB
Markdown
269 lines
5.1 KiB
Markdown
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### 2019-04-02
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Vue屏幕宽度自适应：
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<https://blog.csdn.net/qq_25386583/article/details/77161478>
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<https://blog.csdn.net/xuaner8786/article/details/81565219>
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### 2019-04-07
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- 控制iframe中的页面只显示一部分：<https://blog.csdn.net/iteye_18722/article/details/81918563>
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### 2019-04-09
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```javascript
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Date.parse("2019/04/20 18:14:00")
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```
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上方代码转换的结果，单位是`毫秒`，不是秒。
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### 2019-04-23
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```javascript
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const a = [];
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const b = {};
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console.log(Boolean(a));
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console.log(Boolean(b));
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```
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上方代码的打印结果均为true。 具体解释，可以看我在 `03-JavaScript基础/03-变量的强制类型转换.md`这篇文章里讲到的**转换为Boolean**。
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所以，我们平时在写业务代码的时候，“判断是否为空对象/空数组”，不能直接写成 `if (myObj)`或者`if(myArray)`，会踩坑。
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判断不否为空数组，可以用：
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```javascript
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if (myArray.length)
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```
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判断不为空对象，可以用 ：
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```javascript
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if (JSON.stringify(myObj) !== '{}')
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```
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### 2019-04-26
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我们知道，在移动端页面尅发时，单位一般是采用 rem。
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设计稿如果是750px宽，那么，默认换算的单位如下：**16px = 1rem**。但是这种换算比较麻烦。我们可以在 html里加上如下代码：
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```html
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<style>
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html {
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font-size: 20px;
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font-size: 5.3333333vw;
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}
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</style>
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```
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这样的话，换算单位就变成了：**20px = 1rem**。
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### 2019-05-16
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- 数组随机打乱顺序：<https://www.zhihu.com/question/68330851/answer/262111061>
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最佳的打乱算法是Fisher-Yates算法。
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### 2019-05-16
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Vue的全局变量空间：`this.$root.data`，我们可以在这里面存放数据。比如`this.$root.data.skuIdList`。
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### 2019-05-17
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- css 动画实现闪烁效果：<https://blog.csdn.net/wangxiuyan0228/article/details/80701523>
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### 2019-05-20
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**数组赋值的正确写法**：
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```javascript
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this.todayList.splice(0, 0, ...dataList);
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```
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**对象赋值的正确写法**：
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```javascript
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Object.assign(this.dataObj, dataObj);
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```
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上方代码中，是将`dataObj` 的值追加到`this.dataObj`中。如果对象里属性名相同，会被覆盖。
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### 2019-05-20-css3动画水平/镜像翻转
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参考链接1：<https://www.oschina.net/question/2443483_247744>
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代码实现举例：
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```html
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<!DOCTYPE html>
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<html>
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<head lang="en">
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<meta charset="UTF-8" />
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<title></title>
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<style>
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@keyframes featuresicon {
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0% {
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transform: scaleX(1);
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}
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20% {
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transform: scaleX(1);
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}
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50% {
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transform: scaleX(0);
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}
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80% {
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transform: scaleX(1);
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}
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100% {
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transform: scaleX(1);
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}
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}
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.cube {
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width: 40px;
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height: 40px;
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background: url(images/bg2.png) left 0 no-repeat;
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animation: featuresicon 1.3s linear alternate none infinite;
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}
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body {
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background-color: cornflowerblue;
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}
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</style>
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</head>
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<body>
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<div class="cube"></div>
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</body>
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</html>
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```
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参考链接2：<https://blog.csdn.net/wjnf012/article/details/78679131>
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代码实现：（立体感更强一点）
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title></title>
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<style type="text/css">
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*{
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padding: 0;
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margin: 0;
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}
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.cube{
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display: block;
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color: #ffffff;
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text-align: center;
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width: 40px;
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height: 40px;
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border-radius: 4px;
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/* background-color: #9a6ad8 */
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background: url(images/bg.png) left 0 no-repeat;
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animation: proRotate 1.3s ease-in-out 500ms alternate none infinite;
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}
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@keyframes proRotate {
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0%{transform:perspective(200px) rotateY(180deg);}
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100%{transform:perspective(200px) rotateY(0deg);}
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}
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</style>
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</head>
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<body>
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<div class="test_wrap">
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<div class="cube"></div>
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</div>
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<body>
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</html>
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```
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### 2019-05-22-判断字符串是否为纯中文
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参考链接：https://blog.csdn.net/wozaixiaoximen/article/details/48340061
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### 2019-05-24
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- VScode代码格式化后不符合ESLint风格问题处理：<https://blog.csdn.net/SilenceJude/article/details/81589784>
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### 2019-05-27-针对 text 文本的属性举例
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```css
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&_promote {
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margin-left: 10px;
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display: inline-block;
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height: 20px;
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padding: 4px;
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line-height: 20px;
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background: #fff0f0;
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border-radius: 4px;
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font-size: 20px;
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color: #ff4142;
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white-space: nowrap;
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text-overflow: ellipsis;
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overflow: hidden;
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vertical-align: middle;
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}
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```
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尤其要研究一下 `vertical-align: middle;`这个属性。
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### 2019-06-11
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已知某背景图片的尺寸是：586 * 931。现只截图图片的上面一部分区域（586 * 810）做展示。代码实现如下：
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标签部分：
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```html
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<div class="img"> </div>
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```
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css部分：（重点是 background 属性的写法）
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```css
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.img{
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width: 586rpx;
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height: 810rpx;
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background: url('https://img11.360buyimg.com/jdphoto/s586x931_jfs/t1/27766/15/3237/102443/5c258955Ee307620e/21a744b0d2e065b3.png') 0 0/cover no-repeat;
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margin: 0 auto;
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}
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```
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