TypeScript nerv-shared.isNullOrUndef函數代碼示例

export function unmount (vnode, parentDom?) {
  if (isInvalid(vnode)) {
    return
  }
  const vtype = vnode.vtype
  // Bitwise operators for better performance
  // see: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators
  const dom = vtype & VType.Composite ? vnode.component.dom : vnode.dom

  if ((vtype & (VType.Composite | VType.Stateless)) > 0) {
    options.beforeUnmount(vnode)
    vnode.destroy()
  } else if ((vtype & VType.Node) > 0) {
    const { props, children, ref } = vnode
    unmountChildren(children)
    for (const propName in props) {
      if (isAttrAnEvent(propName)) {
        detachEvent(dom, propName, props[propName])
      }
    }
    if (ref !== null) {
      Ref.detach(vnode, ref, dom)
    }
  }

  if (!isNullOrUndef(parentDom) && !isNullOrUndef(dom)) {
    parentDom.removeChild(dom)
  }
  // vnode.dom = null
}

function patchProps (
  domNode: Element,
  nextProps: Props,
  previousProps: Props,
  lastVnode: VNode,
  isSvg?: boolean
) {
  for (const propName in previousProps) {
    const value = previousProps[propName]
    if (isNullOrUndef(nextProps[propName]) && !isNullOrUndef(value)) {
      if (isAttrAnEvent(propName)) {
        detachEvent(domNode, propName, value)
      } else if (propName === 'dangerouslySetInnerHTML') {
        domNode.textContent = ''
      } else if (propName === 'className') {
        domNode.removeAttribute('class')
      } else {
        domNode.removeAttribute(propName)
      }
    }
  }
  for (const propName in nextProps) {
    patchProp(
      domNode,
      propName,
      previousProps[propName],
      nextProps[propName],
      lastVnode,
      isSvg
    )
  }
}

function isKeyed (lastChildren: VNode[], nextChildren: VNode[]): boolean {
  return (
    nextChildren.length > 0 &&
    !isNullOrUndef(nextChildren[0]) &&
    !isNullOrUndef(nextChildren[0].key) &&
    lastChildren.length > 0 &&
    !isNullOrUndef(lastChildren[0]) &&
    !isNullOrUndef(lastChildren[0].key)
  )
}

function attachNewNode (parentDom, newNode, nextNode) {
  if (isNullOrUndef(nextNode)) {
    parentDom.appendChild(newNode)
  } else {
    parentDom.insertBefore(newNode, nextNode)
  }
}

export function mountComponent (vnode: FullComponent, parentContext: object, parentComponent) {
  const ref = vnode.props.ref
  vnode.component = new vnode.type(vnode.props, parentContext)
  const component = vnode.component
  if (isComponent(parentComponent)) {
    component._parentComponent = parentComponent
  }
  if (isFunction(component.componentWillMount)) {
    errorCatcher(() => {
      (component as any).componentWillMount()
    }, component)
    component.state = component.getState()
  }
  component._dirty = false
  const rendered = renderComponent(component)
  component._rendered = rendered
  if (isFunction(component.componentDidMount)) {
    readyComponents.push(component)
  }
  if (!isNullOrUndef(ref)) {
    readyComponents.push(() => Ref.attach(vnode, ref, component.dom))
  }
  const dom = (vnode.dom = component.dom = mountVNode(
    rendered,
    getChildContext(component, parentContext),
    component
  ) as Element)
  component._disable = false
  return dom
}

function setStyle (domStyle, style, value) {
  if (isNullOrUndef(value) || (isNumber(value) && isNaN(value))) {
    domStyle[style] = ''
    return
  }
  if (style === 'float') {
    domStyle['cssFloat'] = value
    domStyle['styleFloat'] = value
    return
  }
  domStyle[style] =
    !isNumber(value) || IS_NON_DIMENSIONAL.test(style) ? value : value + 'px'
}

export function unmountComponent (vnode: FullComponent) {
  const component = vnode.component
  if (isFunction(component.componentWillUnmount)) {
    errorCatcher(() => {
      (component as any).componentWillUnmount()
    }, component)
  }
  component._disable = true
  unmount(component._rendered)
  if (!isNullOrUndef(vnode.props.ref)) {
    Ref.detach(vnode, vnode.props.ref, vnode.dom as any)
  }
}

export function patch (
  lastVnode,
  nextVnode,
  lastDom: Element,
  context: object,
  isSvg?: boolean
) {
  lastDom = (lastVnode && lastVnode.dom) || lastDom
  if (isVText(nextVnode) && isVText(lastVnode)) {
    return patchVText(lastVnode, nextVnode)
  }
  let newDom
  if (isSameVNode(lastVnode, nextVnode)) {
    if (isVNode(nextVnode)) {
      isSvg = isNullOrUndef(isSvg) ? lastVnode.isSvg : isSvg
      if (isSvg) {
        nextVnode.isSvg = isSvg
      }
      patchProps(lastDom, nextVnode.props, lastVnode.props, lastVnode, isSvg)
      patchChildren(
        lastDom,
        lastVnode.children,
        nextVnode.children,
        context,
        isSvg as boolean
      )
      if (nextVnode.ref !== null) {
        Ref.update(lastVnode, nextVnode, lastDom)
      }
      newDom = lastDom
    } else if (isWidget(nextVnode)) {
      newDom = nextVnode.update(lastVnode, nextVnode, context, lastDom)
      options.afterUpdate(nextVnode)
    }
    (nextVnode as any).dom = newDom
  } else {
    const parentNode = lastDom.parentNode
    const nextSibling = lastDom.nextSibling
    unmount(lastVnode, parentNode)
    newDom = createElement(nextVnode, isSvg, context)
    if (nextVnode !== null) {
      nextVnode.dom = newDom
    }
    if (parentNode !== null) {
      parentNode.insertBefore(newDom as Node, nextSibling)
    }
  }
  return newDom
}

function createElement (
  vnode: VirtualNode | VirtualNode[],
  isSvg?: boolean,
  parentContext?,
  parentComponent?
): Element | Text | Comment | DocumentFragment | null {
  let domNode
  if (isValidElement(vnode)) {
    const vtype = vnode.vtype
    if (vtype & (VType.Composite | VType.Stateless)) {
      domNode = (vnode as CompositeComponent).init(parentContext, parentComponent)
      options.afterMount(vnode as CompositeComponent)
    } else if (vtype & VType.Text) {
      domNode = doc.createTextNode((vnode as any).text);
      (vnode as any).dom = domNode
    } else if (vtype & VType.Node) {
      domNode = mountVNode(vnode as any, isSvg, parentContext, parentComponent)
    } else if (vtype & VType.Void) {
      domNode = (vnode as any).dom
    }
  } else if (isString(vnode) || isNumber(vnode)) {
    domNode = doc.createTextNode(vnode as string)
  } else if (isNullOrUndef(vnode) || (vnode as any) === false) {
    domNode = doc.createTextNode('')
  } else if (isArray(vnode)) {
    domNode = doc.createDocumentFragment()
    vnode.forEach((child) => {
      if (!isInvalid(child)) {
        const childNode = createElement(child, isSvg, parentContext, parentComponent)
        if (childNode) {
          domNode.appendChild(childNode)
        }
      }
    })
  } else {
    throw new Error('Unsupported VNode.')
  }
  return domNode
}

export function reRenderComponent (prev: CompositeComponent, current: CompositeComponent) {
  const component = (current.component = prev.component)
  const nextProps = current.props
  const nextContext = component.context
  component._disable = true
  if (isFunction(component.componentWillReceiveProps)) {
    errorCatcher(() => {
      (component as any).componentWillReceiveProps(nextProps, nextContext)
    }, component)
  }
  component._disable = false
  component.prevProps = component.props
  component.prevState = component.state
  component.prevContext = component.context
  component.props = nextProps
  component.context = nextContext
  if (!isNullOrUndef(nextProps.ref)) {
    Ref.update(prev, current)
  }
  updateComponent(component)
  return component.dom
}