你一定会用到的 12个前端小知识

1. 垂直居中

html

<div class="parent">
    <div class="child">东西南北我居中</div>
</div>

css

.parent {
  border: 3px solid #eee;
  background: #f5f6f9;
  height: 100px;
  /* 关键代码 */
  display: flex;
  justify-content: center;
  align-items: center;
}
.child{
  font-size: 14px;
  font-weight: 400;
}

效果图

2. calc

html

<div class="parent">
    <div class="child"></div>
</div>

// 绘制Progress 进度条
.parent {
  border: 1px solid #eee;
  background: #ebeef5;
  border-radius: 4px;
  width: 200px;
  height: 6px;
  overflow: hidden;
}

.child {
  /* 关键代码 */
  width: calc(100% - 50%);
  background: #409eff;
  height: 100%;
}

3. 文本超出显示...

html

<div class="txt">
    如果上天能够给我重来一次的机会，我不会用爱换一场英雄梦.青春不再是遗憾了半生匆匆的别离，我会对她说三个字我爱你
</div>

css

.txt {
  border: 1px solid #eee;
  background: #ebeef5;
  border-radius: 4px;
  width: 400px;
  height: 30px;
  font-size: 14px;
  line-height: 30px;
  padding-left: 5px;
  color: #333;
  /* 关键代码 */
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

效果图

4. 设置input placeholder样式

html

<div class="parent">
    <input class="placeholder" type="text" placeholder="注重细节，从小事做起，因为你根本做不了大事" />
  </div>

.parent{
  width: 360px;
}
.placeholder {
  -webkit-appearance: none;
  background-color: #fff;
  background-image: none;
  border-radius: 4px;
  border: 1px solid #dcdfe6;
  box-sizing: border-box;
  color: #606266;
  display: inline-block;
  font-size: 14px;
  height: 40px;
  line-height: 40px;
  outline: none;
  padding: 0 15px;
  transition: border-color .2s cubic-bezier(.645, .045, .355, 1);
  width: 100%;
}

/* 关键代码 */
.placeholder::-webkit-input-placeholder {
  color: #1E90FF;
}

效果图

5. 移除type="number"尾部的箭头

html

<div class="parent">
    <input type="number" value="99" />
    <input class="spin" type="number" value="99" />
</div>

css

.parent {
  width: 360px;
}

.spin,
input {
  -webkit-appearance: none;
  background-color: #fff;
  background-image: none;
  border-radius: 4px;
  border: 1px solid #dcdfe6;
  box-sizing: border-box;
  color: #606266;
  display: inline-block;
  font-size: inherit;
  height: 40px;
  line-height: 40px;
  outline: none;
  padding: 0 15px;
  transition: border-color .2s cubic-bezier(.645, .045, .355, 1);
  width: 100%;
  font-size: 14px;
  color: #1E90FF;
}

.spin{
  margin-top: 16px;
}
/* 关键代码 */
.spin::-webkit-inner-spin-button {
  -webkit-appearance: none;
}

.input::-webkit-inner-spin-button {
  -webkit-appearance: none;
}

效果图

6. 移除input状态线

html

  <div class="container">
    <input placeholder="作为好朋友，长得比我丑，是对我最起码的尊重。" />
    <input class="outline" placeholder="作为好朋友，长得比我丑，是对我最起码的尊重。" />
  </div>

css

.container {
  width: 360px;
}

input {
  -webkit-appearance: none;
  background-color: #fff;
  background-image: none;
  border-radius: 4px;
  border: 1px solid #dcdfe6;
  box-sizing: border-box;
  color: #606266;
  display: inline-block;
  font-size: 14px;
  height: 40px;
  line-height: 40px;
  width: 100%;
  padding: 0 15px;
  transition: border-color .2s cubic-bezier(.645, .045, .355, 1);
  width: 100%;
}

/* 关键代码 */
.outline {
  outline: none;
  margin-top: 16px;
}

效果图

7. 选择器

html

<ul class="container">
    <li>我是一条鱼,曾经快乐的游来游去</li>
    <li>我是一条鱼,曾经快乐的游来游去</li>
    <li>我是一条鱼,曾经快乐的游来游去</li>
    <li>我是一条鱼,曾经快乐的游来游去</li>
</ul>

css

* {
  padding: 0;
}
.container {
  width: 360px;
}
.container li {
  -webkit-appearance: none;
  border-radius: 4px;
  color: #606266;
  display: inline-block;
  font-size: 14px;
  height: 40px;
  line-height: 40px;
  width: 100%;
  padding: 0 15px;
  margin-bottom: 8px;
}
/* 关键代码 */
.container li:first-child {
  border: 1px solid #7CFC00;
}
.container li:last-child {
  border: 1px solid #00BFFF;
}
.container li:nth-child(even) {
  color: #FFC0CB;
}
.container li:not(:last-child) {
  background: #F5F5F5;
}

效果图

8. 自定义文本选择样式

html

<div class="txt">
    一万和一百万都是一样的，因为我都没有!
</div>
<div class="txt">
    一万和一百万都是一样的，因为我都没有!
</div>

css

txt::selection {
  color: #ffd476;
}

效果图

9. 改变光标颜色

html

<div class="container">
    <input class="cursor" />
</div>

css

.container {
  width: 360px;
}

input {
  -webkit-appearance: none;
  background-color: #fff;
  background-image: none;
  border-radius: 4px;
  border: 1px solid #dcdfe6;
  box-sizing: border-box;
  color: #606266;
  display: inline-block;
  font-size: 14px;
  height: 40px;
  line-height: 40px;
  width: 100%;
  padding: 0 15px;
  transition: border-color .2s cubic-bezier(.645, .045, .355, 1);
  width: 100%;
}

/*  关键代码 */
.cursor {
  caret-color: #ffd476;
}

效果图

10. 图片自适应

html

<div class="container">
    <img src="./1.jpeg" class="img"/>
</div>

css

.container {
  width: 360px;
  height: 120px;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* 关键代码 */
.img {
  max-width: 100%;
  max-height: 100%;
  width: auto;
  height: auto;
}

效果图

.img {
    max-width:100%;
    max-height:100%;
    width:auto;
    height:auto;
}