_onEvent (event) {
    const element = event.target
    const isField = element === this.dom.field
    const isValue = (
      element === this.dom.value ||
      element === this.dom.checkbox ||
      element === this.dom.select)

    if (isField || isValue) {
      const info = {
        field: this.getField(),
        path: this.getPath()
      }

      // For leaf values, include value
      if (isValue && !this._hasChilds()) {
        info.value = this.getValue()
      }

      this.editor.options.onEvent(info, event)
    }
  }
Trigger external onEvent provided in options if node is a JSON field or
value.
Information provided depends on the element, value is only included if
event occurs in a JSON value:
{field: string, path: {string|number}[] [, value: string]}
@param {Event} event
@private