什么是JSX?

JSX就是Javascript和XML结合的一种格式。React发明了JSX，利用HTML语法来创建虚拟DOM。当遇到<，JSX就当HTML解析，遇到{就当JavaScript解析.

render (h) {
  return (
    <div
      // normal attributes or component props.
      id="foo"
      // DOM properties are prefixed with `domProps`
      domPropsInnerHTML="bar"
      // event listeners are prefixed with `on` or `nativeOn`
      onClick={this.clickHandler}
      // onClick={this.clickHandler.bind(this, arguments)}
      nativeOnClick={this.nativeClickHandler}
      // other special top-level properties
      class={{ foo: true, bar: false }}
      style={{ color: 'red', fontSize: '14px' }}
      key="key"
      ref="ref"
      // assign the `ref` is used on elements/components with v-for
      refInFor
      slot="slot">
    </div>
  )
}

//或者
render (h) {
  return h('div', {
    // Component props
    props: {
      msg: 'hi',
      onCustomEvent: this.customEventHandler
    },
    // normal HTML attributes
    attrs: {
      id: 'foo'
    },
    // DOM props
    domProps: {
      innerHTML: 'bar'
    },
    // Event handlers are nested under "on", though
    // modifiers such as in v-on:keyup.enter are not
    // supported. You'll have to manually check the
    // keyCode in the handler instead.
    on: {
      click: this.clickHandler
    },
    // For components only. Allows you to listen to
    // native events, rather than events emitted from
    // the component using vm.$emit.
    nativeOn: {
      click: this.nativeClickHandler
    },
    // class is a special module, same API as `v-bind:class`
    class: {
      foo: true,
      bar: false
    },
    // style is also same as `v-bind:style`
    style: {
      color: 'red',
      fontSize: '14px'
    },
    // other special top-level properties
    key: 'key',
    ref: 'ref',
    // assign the `ref` is used on elements/components with v-for
    refInFor: true,
    slot: 'slot'
  })
}