vue に実装されたライフサイクル フックの簡単な分析

<div id="app">
    <aC />
    <bC />
</div>

// a组件
created() {
    console.log('aC')
  },
mounted() {
  debugger
  console.log('aM')
},

// b组件
created() {
    console.log('bC')
  },
mounted() {
  debugger
  console.log('bM')
},

function createComponent (vnode, insertedVnodeQueue, parentElm, refElm) {
    var i = vnode.data;
    if (isDef(i)) {
      var isReactivated = isDef(vnode.componentInstance) && i.keepAlive;
      if (isDef(i = i.hook) && isDef(i = i.init)) {
        i(vnode, false /* hydrating */);
      }
      if (isDef(vnode.componentInstance)) {
        initComponent(vnode, insertedVnodeQueue);
				// 最终组件创建完后会走到这里 把组件对应的el插入到父节点
        insert(parentElm, vnode.elm, refElm);
        if (isTrue(isReactivated)) {
          reactivateComponent(vnode, insertedVnodeQueue, parentElm, refElm);
        }
        return true
      }
    }
  }

invokeInsertHook(vnode, insertedVnodeQueue, isInitialPatch);

function invokeInsertHook (vnode, queue, initial) {
    // delay insert hooks for component root nodes, invoke them after the
    // element is really inserted
    if (isTrue(initial) && isDef(vnode.parent)) {
      vnode.parent.data.pendingInsert = queue;
    } else {
      for (var i = 0; i < queue.length; ++i) {
        queue[i].data.hook.insert(queue[i]);
      }
    }
  }

insert: function insert (vnode) {
    var context = vnode.context;
    var componentInstance = vnode.componentInstance;
    if (!componentInstance._isMounted) {
      componentInstance._isMounted = true;
      callHook(componentInstance, 'mounted');
    }
    if (vnode.data.keepAlive) {
      if (context._isMounted) {
        // vue-router#1212
        // During updates, a kept-alive component's child components may
        // change, so directly walking the tree here may call activated hooks
        // on incorrect children. Instead we push them into a queue which will
        // be processed after the whole patch process ended.
        queueActivatedComponent(componentInstance);
      } else {
        activateChildComponent(componentInstance, true /* direct */);
      }
    }
  },

function invokeInsertHook (vnode, queue, initial) {
    // delay insert hooks for component root nodes, invoke them after the
    // element is really inserted
    if (isTrue(initial) && isDef(vnode.parent)) {
      vnode.parent.data.pendingInsert = queue;
    } else {
      for (var i = 0; i < queue.length; ++i) {
        queue[i].data.hook.insert(queue[i]);
      }
    }
  }

// 在patch 开始时候 定义了insertedVnodeQueue为一个空数组
var insertedVnodeQueue = [];

function initComponent (vnode, insertedVnodeQueue) {
    if (isDef(vnode.data.pendingInsert)) {
      insertedVnodeQueue.push.apply(insertedVnodeQueue, vnode.data.pendingInsert);
      vnode.data.pendingInsert = null;
    }
    vnode.elm = vnode.componentInstance.$el;
    if (isPatchable(vnode)) {
			// ⚠️注意这个方法 
      invokeCreateHooks(vnode, insertedVnodeQueue);
      setScope(vnode);
    } else {
      // empty component root.
      // skip all element-related modules except for ref (#3455)
      registerRef(vnode);
      // make sure to invoke the insert hook
      insertedVnodeQueue.push(vnode);
    }
  }

function invokeCreateHooks (vnode, insertedVnodeQueue) {
    for (var i$1 = 0; i$1 < cbs.create.length; ++i$1) {
      cbs.create[i$1](emptyNode, vnode);
    }
    i = vnode.data.hook; // Reuse variable
    if (isDef(i)) {
      if (isDef(i.create)) { i.create(emptyNode, vnode); }
	     // 把当前vnode push 到了insertedVnodeQueue
      if (isDef(i.insert)) { insertedVnodeQueue.push(vnode); }
    }
  }