element-ui文件上传做类型大小的限制

上代码：

<div class="filebox">
    <el-upload class="upload-demo" :action="url" :on-preview="handlePreview" :on-remove="handleRemove" 
　　　　　　multiple :limit="limitnum" :on-exceed="handleExceed" :file-list="fileList" :beforeUpload="beforeAvatarUpload">
    <el-button size="mini" type="primary">点击上传</el-button>
    <div slot="tip" class="el-upload__tip">只能上传jpg/png文件，且不超过500kb</div>
    </el-upload>
</div>

:beforeUpload="beforeAvatarUpload" 底下有方法重要在这里：
methods里面写beforeAvatarUpload这个方法

　　　　　　beforeAvatarUpload(file) {                 
                var testmsg=file.name.substring(file.name.lastIndexOf(\'.\')+1)                
                const extension = testmsg === \'xls\'
                const extension2 = testmsg === \'xlsx\'
                const isLt2M = file.size / 1024 / 1024 < 10
                if(!extension && !extension2) {
                    this.$message({
                        message: \'上传文件只能是 xls、xlsx格式!\',
                        type: \'warning\'
                    });
                }
                if(!isLt2M) {
                    this.$message({
                        message: \'上传文件大小不能超过 10MB!\',
                        type: \'warning\'
                    });
                }
                return extension || extension2 && isLt2M
            }

想要什么限制加什么限制就好。