vue input限制只能输入正整数

<el-form :model="processCategoryForm" :rules="processCategoryFormParentRules" ref="processCategoryForm"
               label-width="100px"
               label-position="right" style="width: 480px; margin-left:50px;">
        <el-row>
          <el-col>
            <el-form-item label="分类名称" prop="name">
              <el-input v-model="processCategoryForm.name" placeholder="请输入分类名称"></el-input>
            </el-form-item>
          </el-col>
        </el-row>
 </el-form>

processCategoryFormParentRules: {
          name: [{required: true, message: '分类是必填项', trigger: 'blur'}],
          sort: [{required: false,message: '序号是必填项', trigger: 'blur'},{validator:isNumber,trigger:"blur"}],
        },

data() {
     // 限制正整数
     var isNumber=(rule,value,callback)=>{
       let ret=/^([0-9]*)$/;
       console.log(this.processCategoryForm)
       if(value===''){
         callback(new Error('不能为空'))
       }else if(!ret.test(this.processCategoryForm.sort)){
         callback(new Error('输入整数'))
       }else{
         callback()
       }
     }
     return {}