ReactJS Promise-\u this.setExitAnimation未定义

不过,请回复我:

_this.setExitAnimation未定义 下面是我的代码片段:

/***** HERE TRIGGER THE setAnimation's PROCESS THEN INJECT 
UPDATED ANIATION IN COMPONENT *****/
textAnimation=()=>{            

    // CALL THE PROMISE'S CHAIN
      this.setState({elementType:"text"}, 
        () => this.routeAnimationPosition
          .then((anim) => { 
            console.log("promise resolved: ", anim)
            // set new animations
        this.setState({firstLineAnimation:anim}, 
          () =>     console.log("after setState textAnimation: ", this.state.textAnimation)
          )
{...}

/***** HERE START THE PROMISE'S CHAIN TO UPDATE ANIMATION'S NAME *****/

routeAnimationPosition= new Promise((resolve, reject)=>{ 
  console.log("in routeAnimationPosition")
  if(this.state.exitLoop){ 
    this.setExitAnimation.then((anim)=> resolve(anim)); 
  }else{ 
    this.setEnterAnimation.then((anim)=> resolve(anim));
  }  
})

setEnterAnimation=new Promise((resolve, reject)=>{ 
  console.log("in setEnterAnimation")
  if(this.state.elementType ==="text"){
    if(this.state.currentView % 2 === 0){ 
      this.setState({textAnimation:enterDownAnimation});
      resolve(enterDownAnimation);
{...}

我不知道怎么回事,我觉得我的动画制作过程是公平的, 任何暗示都很好,