如何修复 TypeError：无法读取未定义的属性？

Question

My UI crashes and I am getting the following error:

TypeError: Cannot read property 'filter' of undefined

at v (helper.js:16)
at i (lodash.min.js:9)
at t (lodash.min.js:59)
at value (CheckAll.js:15)

Here's a snippet of the helper.js code:

export const updatedChecked = (items, checked) => items.map(item => ({ ...item, checked }));

export const filterChecked = (items, checked) => items.filter(item => item.checked === checked);

export const moveAtTheTop = (items, itemIds) => pureReverse(itemIds).reduce((acc, v) => {
 const toCutIndex = acc.findIndex(item => item.id === v);
 const toCut = acc.splice(toCutIndex, 1)[0];
 toCut.checked = true;
 acc.unshift(toCut);
 return acc;
}, updateChecked(items, false));

export const normalizeSrcItems = items => filterChecked(items, true).map(item => item.id);

Answer 1

It's probably because you send undefined in items argument when you call normalizeSrcItems . You need to check it where you call it

if (items) {
  normalizeSrcItems(items)
}

, or check why you have empty items, perhaps you get it in wrong way

Answer 2

Obviously, calling

items.filter(...)

Looks like items is undefined. Quick fix is:

(items || []).filter(...)

But it might not solve the problem, why items are undefined.