vue回调函数无法更改model的值

data:{

isUpload:true,

} 

 getFile(event) {
//选择图片
               let eventId = event.target.id;
                 let type=  testImgType(eventId);
                if(!type){
                    return;
                }
                let fileName = event.target.files[0].name;
                let max = testMaxSize(event.target.files[0],1024*3*1024);
                if(!max){
                    return;
                }
                let width = testImgWidthHeight(eventId,1920,1080,function (res) {
                    if (!res) {
                        this.isUpload=false;
                        console.log( this.isUpload)
                        vue.$message({
                            message: ‘图片尺寸不正确！‘,
                            type: ‘warning‘
                        });
                    }else {
                        this.isUpload=true;
                        console.log( this.isUpload)
                    }
                });
                if(eventId==‘addWorkFile‘){
                    this.file = event.target.files[0];
                    this.workFileName=fileName;
                }else{
                    this.file2 = event.target.files[0];
                    this.personFileName=fileName;
                }
            },
//点击上传
            submitForm(event) {
                console.log(this.isUpload)
                if(!this.isUpload){
                    console.log(this.isUpload)
                    return;
                }