Javascript 返回未定义的值

Question

这是我的 nuxt js 代码中的一种方法。

this.allCampusWithDeaprtments = campusData.map(
          (item, index) => {
              const schoolData = this.deptInsights.filter((row) => {
                  return row.unit === item.unit;
              }).map(row => {
                  // row.departmentData = row.departmentData || []; 
                  // row.departmentData.push(...this.depts.filter((d) => {
                  //     return d.sisSchoolId === row.sisSchoolId;
                  // }));
                  // return row;
                  const departmentData = this.depts.filter(
                  d => d.sisSchoolId === row.sisSchoolId
                );
                return departmentData
              });

              console.log('department', departmentData);
              // );
              item.id = `toggle-${index}`;
              return {
                  ...item,
                  schoolData,
                  // departmentData,
                  hasOerData: false
              };
          }
      );

departmentData没有返回任何值。 可能是什么问题呢？ 我想要与代码中提到的情况相匹配的数据

Answer 1

继续同事@sebastian-simon 的推理

您的常量在 scope 中是私有的。 因此，它没有定义。 阅读这篇文章。

试试这样：

this.allCampusWithDeaprtments = campusData.map(
let departmentData = null

(item, index) => {
    const schoolData = this.deptInsights.filter((row) => {
        row.unit === item.unit
        departmentData = this.depts.filter((d) => {
            d.sisSchoolId === row.sisSchoolId;
            return departmentData
        })

    }
    );

    console.log('department', departmentData);
    // );
    item.id = `toggle-${index}`;
    return {
        ...item,
        schoolData,
        departmentData,
        hasOerData: false
    };
});

Answer 2

据我所知，可能有两种情况：-

1. 根据您在campusData数组变量中传递的数据，您的条件不满足。
2. 你没有返回departmentData ，

return const departmentData = this.depts.filter((d) => {...

让我知道，如果它有帮助。

Answer 3

我认为你的问题出在这里：

const departmentData = this.depts.filter((d) => {
            d.sisSchoolId === row.sisSchoolId;
            return departmentData // 
        })

过滤器回调需要返回 boolean。 您正在检查条件d.sisSchoolId === row.sisSchoolId; 但不返回它，而是返回departmentData 。 所以请记住这一点，您的过滤器代码不应该是：

this.allCampusWithDeaprtments = campusData.map(
    (item, index) => {
        let departmentData = [];
        const schoolData = this.deptInsights.filter((row) => {
            departmentData.push(...this.depts.filter((d) => {
                return d.sisSchoolId === row.sisSchoolId;
            }));
            return row.unit === item.unit;

        });

        console.log('department', departmentData);
        // );
        item.id = `toggle-${index}`;
        return {
            ...item,
            schoolData,
            departmentData,
            hasOerData: false
        };
    }
);

编辑新结构

this.allCampusWithDeaprtments = campusData.map(
    (item, index) => {
        // let departmentData = [];
        const schoolData = this.deptInsights.filter((row) => {
            return row.unit === item.unit;
        }).map(row => {
            row.departmentData = row.departmentData || []; 
            row.departmentData.push(...this.depts.filter((d) => {
                return d.sisSchoolId === row.sisSchoolId;
            }));
            return row;
        });

        // console.log('department', departmentData);
        // );
        item.id = `toggle-${index}`;
        return {
            ...item,
            schoolData,
            // departmentData,
            hasOerData: false
        };
    }
);