iterate-objects-safely

SKILL.md

Iterating over objects in TypeScript is surprisingly tricky. The for...in loop infers keys as string rather than the object's keys, leading to indexing errors. This happens because objects can have additional properties beyond their declared type (structural typing), and for...in includes inherited properties.

Understanding safe iteration patterns helps you avoid any types and type assertions while correctly handling object traversal.

Use Object.entries for safe iteration over any object. Use for...in with keyof assertions only when you know the exact shape. Consider Map for guaranteed type safety.

在迭代对象键和值时使用。当 for...in 循环产生类型错误时使用。当 Object.entries 返回任何类型时使用。在处理原型污染问题时使用。在考虑地图与对象时使用。 来源：marius-townhouse/effective-typescript-skills。

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