1. var id = 0;
    2. function Dep(){
    3.     this.id = id++;
    4.   this.subs = [];
    5. }
    6. Dep.prototype.addSub = function(watcher){
    7.     this.subs.push(watcher);
    8. }
    9. Dep.prototype.depend = function(){
    10.     if(Dep.target){
    11.       Dep.target.addDep(this);
    12.   }
    13. }
    14. Dep.prototype.remove = function(sub){
    15.     this.subs.splice(this.subs.indexOf(sub),1);
    16. }
    18. let stacks = [];// 存放watcher
    19. function pushTarget (watcher){
    20.   Dep.target = watcher;
    21.   stack.push(watcher);
    22. }
    24. function popTarget(){
    25.   stack.pop();
    26.     Dep.target = stack[stack.length-1]
    27. }
    1. var id = 0,
    2.     callbacks = [],
    3.     queue = [],
    4.     has = {};
    5. function Watcher(vm,exprOrFn,cb,opts){
    6.   this.id = id++;
    7.   this.vm = vm;
    8.   cb = typeof cb ==='function'?cb:function(){};
    9.   if(typeof exprOrFn === 'function'){
    10.       this.getter = exprOrFn;
    11.   }
    12.   this.deps=[];
    13.   this.depIds = new Set();
    14.   this.opts = opts;
    15.   this.get();
    16. }
    18. // 在watcher中添加dep
    19. Watcher.prototype.addDep = function(dep){
    20.     var id = dep.id;
    21.   if(!this.depIds.has(id)){
    22.       this.deps.push(dep);
    23.     this.depIds.add(id);
    24.     // 在dep中添加watcher
    25.     dep.addSub(this);
    26.   }
    27. }
    29. Watcher.prototype.get = function(){
    30.     pushTarget();
    31.   this.getter();
    32.   popTarget();
    33. }
    35. Watcher.prototype.update = function (){
    36.     queueWatcher(this);
    37. }
    39. Watcher.prototype.run = function(){
    40.   this.get();
    41. }
    44. function queueWatcher(vm){
    45.   var id =  vm.id;
    46.   if(!has[id]){
    47.       queue.push(vm);
    48.     has[id] = true;
    49.     nextTick(flushQue)
    50.   }
    51. }
    53. // 清空队列
    55. function flushQue(){
    56.     queue.forEach(watcher=>wathcer.run());
    57.   queue = [];
    58.   has = {};
    59. }
    61. function nextTick(cb){
    62.     callbacks.push(cb);
    63.   let timerFunction = ()=>{
    64.       flushCallBacks();
    65.   }
    66.     if(Promise){
    67.       return Promise.resolve().then(timerFunction);
    68.   }
    69.   if(MutationOberserver){
    70.       let observe = new MutationObserver(timerFunction);
    71.     let textNode = document.createTextNode(10);
    72.     observe.observe(textNode,{charactorData:true});
    73.     textNode.textContent = 20;
    74.     return true
    75.   }
    76.   if(setImmediate){
    77.       return setImmediate(timerFunction)
    78.   }
    79.   setTimeout(timerFunction,0);
    80. }