解决vue的变量在settimeout内部效果失效的问题

  var self=this;
    this.toastrVal = inVal;
    this.loadState = true;
    this.noBg = bgState;
    setTimeout(function () {
     self.loadState = false;
    }, 3000)

export default {
 data () {
  return {
   left: -9999,
   bottom: -9999
  }
 },
 methods: {
  cancelMask: function () {
   setTimeout(() => {
    this.bottom = 0;
    this.left = 0;
   }, 500);
  }
 }
}

export default {
 data () {
  return {
   left: -9999,
   bottom: -9999
  }
 },
 methods: {
  cancelMask: function () {
   var that = this;
   setTimeout(function () {
    that.bottom = 0;
    that.left = 0;
   }, 500);
  }
 }
}