nuxt.js 中使用ant-design组件按需加载来优化项目文件大小

nuxt.js 是服务端渲染的框架，性能优化非常重要。默认在项目中使用 ant-design 是全量引入的，这其中是有很多用不到的组件的，无形中增加的文件大小，从而拉低了页面加载速度，所以说，最简单的性能优化，就是按需引入

1. 安装 ant-design

npm i ant-design-vue -S 或者 cnpm i ant-design-vue -S

已安装的跳过这一步

2. 引入 ant-design 中自己需要的组件

在项目文件夹 plugin 下面新建一个 antd-ui.js 的文件

import Vue from "vue";
import {
    Button,
    Anchor,
    Skeleton,
    Icon,
    Card,
    BackTop,
    Tag,
    Tooltip,
    Avatar,
    Rate,
    Affix,
    Alert,
    message
} from "ant-design-vue";
Vue.use(Button)
    .use(Anchor)
    .use(Skeleton)
    .use(Icon)
    .use(Card)
    .use(BackTop)
    .use(Tag)
    .use(Tooltip)
    .use(Avatar)
    .use(Rate)
    .use(Affix)
    .use(Alert)
    .use(message);

Vue.prototype.$message = message;
message.config({
    top: `70px`,
    duration: 2,
    maxCount: 3
});

然后，在 nuxt.config.js 中使用，加在配置对象的 plugins 中

export default {
    plugins: [
        "@/plugins/antd-ui"
    ]
}

现在只是 js 文件按需加载了，还有这些组件的样式我们需要载入

3. 引入组件的样式

同样的也是找到配置对象 的根节点的 CSS

export default {
    css: [
        "ant-design-vue/lib/button/style/index.css",
        "ant-design-vue/lib/anchor/style/index.css",
        "ant-design-vue/lib/skeleton/style/index.css",
        "ant-design-vue/lib/icon/style/index.css",
        "ant-design-vue/lib/card/style/index.css",
        "ant-design-vue/lib/back-top/style/index.css",
        "ant-design-vue/lib/tag/style/index.css",
        "ant-design-vue/lib/tooltip/style/index.css",
        "ant-design-vue/lib/avatar/style/index.css",
        "ant-design-vue/lib/rate/style/index.css",
        "ant-design-vue/lib/affix/style/index.css",
        "ant-design-vue/lib/alert/style/index.css",
        "ant-design-vue/lib/message/style/index.css"
    ]
}

到这，还没有结束，如果只是这样的话，可能你就会发现，样式和原本的样式有一点点不一样。我们还需要引入 ant-design 的基础样式，大概是以下这些：

html,
body {
  width: 100%;
  height: 100%;
}
input::-ms-clear,
input::-ms-reveal {
  display: none;
}
*,
*::before,
*::after {
  box-sizing: border-box;
}
html {
  font-family: sans-serif;
  line-height: 1.15;
  -webkit-text-size-adjust: 100%;
  -ms-text-size-adjust: 100%;
  -ms-overflow-style: scrollbar;
  -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
}
@-ms-viewport {
  width: device-width;
}
article,
aside,
dialog,
figcaption,
figure,
footer,
header,
hgroup,
main,
nav,
section {
  display: block;
}
body {
  margin: 0;
  color: rgba(0, 0, 0, 0.65);
  font-size: 14px;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe1 UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
  font-variant: tabular-nums;
  line-height: 1.5;
  background-color: #fff;
  font-feature-settings: 'tnum';
}
[tabindex='-1']:focus {
  outline: none !important;
}
hr {
  box-sizing: content-box;
  height: 0;
  overflow: visible;
}
h1,
h2,
h3,
h4,
h5,
h6 {
  margin-top: 0;
  margin-bottom: 0.5em;
  color: rgba(0, 0, 0, 0.85);
  font-weight: 500;
}
p {
  margin-top: 0;
  margin-bottom: 1em;
}
abbr[title],
abbr[data-original-title] {
  text-decoration: underline;
  -webkit-text-decoration: underline dotted;
          text-decoration: underline dotted;
  border-bottom: 0;
  cursor: help;
}
address {
  margin-bottom: 1em;
  font-style: normal;
  line-height: inherit;
}
input[type='text'],
input[type='password'],
input[type='number'],
textarea {
  -webkit-appearance: none;
}
ol,
ul,
dl {
  margin-top: 0;
  margin-bottom: 1em;
}
ol ol,
ul ul,
ol ul,
ul ol {
  margin-bottom: 0;
}
dt {
  font-weight: 500;
}
dd {
  margin-bottom: 0.5em;
  margin-left: 0;
}
blockquote {
  margin: 0 0 1em;
}
dfn {
  font-style: italic;
}
b,
strong {
  font-weight: bolder;
}
small {
  font-size: 80%;
}
sub,
sup {
  position: relative;
  font-size: 75%;
  line-height: 0;
  vertical-align: baseline;
}
sub {
  bottom: -0.25em;
}
sup {
  top: -0.5em;
}
a {
  /* color: #1890ff; */
  text-decoration: none;
  background-color: transparent;
  outline: none;
  cursor: pointer;
  transition: color 0.3s;
  -webkit-text-decoration-skip: objects;
}
a:hover {
  color: #40a9ff;
}
a:active {
  color: #096dd9;
}
a:active,
a:hover {
  text-decoration: none;
  outline: 0;
}
a[disabled] {
  color: rgba(0, 0, 0, 0.25);
  cursor: not-allowed;
  pointer-events: none;
}
pre,
code,
kbd,
samp {
  font-size: 1em;
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, Courier, monospace;
}
pre {
  margin-top: 0;
  margin-bottom: 1em;
  overflow: auto;
}
figure {
  margin: 0 0 1em;
}
img {
  vertical-align: middle;
  border-style: none;
}
svg:not(:root) {
  overflow: hidden;
}
a,
area,
button,
[role='button'],
input:not([type='range']),
label,
select,
summary,
textarea {
  touch-action: manipulation;
}
table {
  border-collapse: collapse;
}
caption {
  padding-top: 0.75em;
  padding-bottom: 0.3em;
  color: rgba(0, 0, 0, 0.45);
  text-align: left;
  caption-side: bottom;
}
th {
  text-align: inherit;
}
input,
button,
select,
optgroup,
textarea {
  margin: 0;
  color: inherit;
  font-size: inherit;
  font-family: inherit;
  line-height: inherit;
}
button,
input {
  overflow: visible;
}
button,
select {
  text-transform: none;
}
button,
html [type="button"],
[type="reset"],
[type="submit"] {
  -webkit-appearance: button;
}
button::-moz-focus-inner,
[type='button']::-moz-focus-inner,
[type='reset']::-moz-focus-inner,
[type='submit']::-moz-focus-inner {
  padding: 0;
  border-style: none;
}
input[type='radio'],
input[type='checkbox'] {
  box-sizing: border-box;
  padding: 0;
}
input[type='date'],
input[type='time'],
input[type='datetime-local'],
input[type='month'] {
  -webkit-appearance: listbox;
}
textarea {
  overflow: auto;
  resize: vertical;
}
fieldset {
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 0;
}
legend {
  display: block;
  width: 100%;
  max-width: 100%;
  margin-bottom: 0.5em;
  padding: 0;
  color: inherit;
  font-size: 1.5em;
  line-height: inherit;
  white-space: normal;
}
progress {
  vertical-align: baseline;
}
[type='number']::-webkit-inner-spin-button,
[type='number']::-webkit-outer-spin-button {
  height: auto;
}
[type='search'] {
  outline-offset: -2px;
  -webkit-appearance: none;
}
[type='search']::-webkit-search-cancel-button,
[type='search']::-webkit-search-decoration {
  -webkit-appearance: none;
}
::-webkit-file-upload-button {
  font: inherit;
  -webkit-appearance: button;
}
output {
  display: inline-block;
}
summary {
  display: list-item;
}
template {
  display: none;
}
[hidden] {
  display: none !important;
}
mark {
  padding: 0.2em;
  background-color: #feffe6;
}
::-moz-selection {
  color: #fff;
  background: #1890ff;
}
::selection {
  color: #fff;
  background: #1890ff;
}
.clearfix {
  zoom: 1;
}
.clearfix::before,
.clearfix::after {
  display: table;
  content: '';
}
.clearfix::after {
  clear: both;
}

最后来看一下按需引入后文件大小的变化

😰 按需引入之前：

🎉 按需引入之后：

效果还是很明显的 ✨ ，由原本的 2.19M 降到了 357.49kb(这只是我这个项目，不同项目按需引入的组件数量不用，最后的大小都不同)

如何生成自己项目的文件报告

上图的视图的生成，我们只需要在 nuxt.config.js 中修改一项配置就可以了

export default {
    build: {
        analyze: true
    }
}

启用了后，运行打包命令 npm run build 后 就会自动生成报告，并在浏览器中打开