获取图片上传前的宽高

var reader = new FileReader();
var that = this;
reader.onload = function(e){
//console.log(e);
    var img = new Image();
    img.src = e.target.result;
    img.onload = function(){

        console.log(this.width, " ", this.height);
        if(this.width != 500 || this.height != 158){
        　　that.$message.error(‘图片宽高不符合尺寸！！‘);
        　　that.$refs.upload.abort();
        　　that.$refs.upload.clearFiles();

    　　}
    }
}
var url = reader.readAsDataURL(file);