18-mini-vue element

实现初始化 element

1. 走 render 方法时，调用 patch ，区分 element 和 component
2. 遇到 element, 代码如下

// renderer.ts
function patch(vnode, container) {
  // 对类型进行区分
  if (typeof vnode.type === 'string') { 
    processElement(vnode, container)
  } else if (isObject(vnode.type)) {
    processComponent(vnode, container)
  }
}
function processElement(vnode, container) {
  mountElement(vnode, container)
}
function mountElement(vnode, container) {
  const { type, props, children } = vnode
  const el = document.createElement(type) 
  if (typeof children === 'string') {
    el.textContent = children
  } else if (Array.isArray(children)) {
    mountChildren(children, el)
  }
  for (let key in props) {
    let val = props[key]
    el.setAttribute(key, val)
  }
  container.append(el)
}
function mountChildren(children, el) {
  children.forEach(vnode => {
    patch(vnode, el)
  })
}