最近在看element-ui的源码，边学习的同时也在简书上做一个笔记。

首先，看一下el-button的源码

//单独列出来太过麻烦，在这里，我就直接注释在代码上了，便于查看
<template>
  <button
    class="el-button"
    @click="handleClick" //点击事件
    :disabled="buttonDisabled || loading" //是否为加载状态
    :autofocus="autofocus" //是否默认聚焦
    :type="nativeType" //el-button中的自定义样式，primary / success / warning / danger / info / text
    :class="[
      type ? 'el-button--' + type : '',
      buttonSize ? 'el-button--' + buttonSize : '',
      {
        'is-disabled': buttonDisabled,//是否禁用状态
        'is-loading': loading,//是否是加载中
        'is-plain': plain,//是否朴素按钮
        'is-round': round,//是否圆角
        'is-circle': circle//是否圆形按钮
      }
    ]"
  >
    <i class="el-icon-loading" v-if="loading"></i>
    <i :class="icon" v-if="icon && !loading"></i> //icon图标
    <span v-if="$slots.default"><slot></slot></span>//插槽，自行百度
  </button>
</template>
<script>
  export default {
    name: 'ElButton',
//此处是定义在公共组件的方法，后面详解provide 和 inject的用法 
    inject: {
      elForm: {
        default: ''
      },
      elFormItem: {
        default: ''
      }
    },
    props: {
      type: {
        type: String,
        default: 'default'
      },
      size: String,
      icon: {
        type: String,
        default: ''
      },
      nativeType: {
        type: String,
        default: 'button'
      },
      loading: Boolean,
      disabled: Boolean,
      plain: Boolean,
      autofocus: Boolean,
      round: Boolean,
      circle: Boolean
    },

    computed: {
      _elFormItemSize() {
        return (this.elFormItem || {}).elFormItemSize;
      },
      buttonSize() {
        return this.size || this._elFormItemSize || (this.$ELEMENT || {}).size;
      },
      buttonDisabled() {
        return this.disabled || (this.elForm || {}).disabled;
      }
    },

    methods: {
//此处是el-button的自定义事件
      handleClick(evt) {
        this.$emit('click', evt);
      }
    }
  };
</script>

以上是el-button组件的所有内容
接下来时候全局注册

import ElButton from './src/button';

/* istanbul ignore next */
ElButton.install = function(Vue) {
  Vue.component(ElButton.name, ElButton);
};

export default ElButton;