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);
 }
 }
}