Question

当我没有将数据保存到数据库时，我可以添加或删除，一旦保存了数据并且我想通过删除它们或添加新值进行更新，就会出现此错误无法定义超过不可写长度的数组末尾的数组索引属性。如何解决此问题？

  const handleDeleteDepartment = (companyIndex, departmentIndex) => {
    if (departmentIndex !== 0) {
      const newCompanies = [...companies];
      newCompanies[companyIndex].children.splice(departmentIndex, 1);
      setCompanies(newCompanies);
    }
  };

Answer 1

在执行此行之前，您需要在此处进行更多检查：

newCompanies[companyIndex].children.splice(departmentIndex, 1);

you want to be sure that newCompanies[companyIndex] exists:

if(newCompanies[companyIndex])

you want to be sure the departmentIndex is not higher than the newCompanies[companyIndex].children length:

departmentIndex < newCompanies[companyIndex]?.children.length

you want to be sure that newCompanies[companyIndex].children is an array:

Array.isArray(newCompanies[companyIndex].children)

这不应该失败：

const handleDeleteDepartment = (companyIndex, departmentIndex) => {
  const newCompanies = [...companies];
  if (departmentIndex !== 0) {
    if (
      newCompanies[companyIndex] &&
      Array.isArray(newCompanies[companyIndex]?.children) &&
      departmentIndex < newCompanies[companyIndex]?.children?.length
    ) {
      newCompanies[companyIndex].children.splice(departmentIndex, 1);
      setCompanies(newCompanies);
    }
  }
};

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