TypeScript HTMLFormControlsCollection namedItem should return only form input elements

u4dcyp6a 于 6个月前发布在 TypeScript

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TypeScript版本： 3.9.2
搜索词： HTMLFormControlsCollection RadioNodeList namedItem
代码

declare const form: HTMLFormElement;

const element = form.elements.namedItem('foo')

if (element && !(element instanceof RadioNodeList)) {
  console.log('eee', element.value) // <<< Property 'value' does not exist on type 'Element'
}

预期行为： 根据 MDN,namedItem() 在 HTMLFormControlsCollection 上只返回一组特定的元素类型。

HTMLFormControlsCollection 应该继承自 HTMLCollectionOf<HTMLButtonElement | HTMLFieldSetElement | HTMLInputElement | HTMLObjectElement | HTMLOutputElement | HTMLSelectElement | HTMLTextAreaElement>
HTMLFormControlsCollection.namedItem() 应该返回 RadioNodeList | HTMLButtonElement | HTMLFieldSetElement | HTMLInputElement | HTMLObjectElement | HTMLOutputElement | HTMLSelectElement | HTMLTextAreaElement | null
RadioNodeList 应该继承自 NodeListOf<HTMLButtonElement | HTMLFieldSetElement | HTMLInputElement | HTMLObjectElement | HTMLOutputElement | HTMLSelectElement | HTMLTextAreaElement>
实际行为：HTMLFormControlsCollection.namedItem() 的返回类型不够具体( Element )。
** playground链接：**https://www.typescriptlang.org/play/?ssl=7&ssc=2&pln=1&pc=1#code/CYUwxgNghgTiAEYD2A7AzgF3gMyTAtgFzwASAKgLIAyAYnvgKIQj4goYDcAUF8uliGat28ALw56AOkEs2GNJJRRWwAJIYWACgDkuJNoCUPAJbZ4mmcKwAya-ACEFoXPjH+UFGBBIzAJSjAxkgAckigVMaYBgbwAN5c8IioaEjMkhBIAOY6ILnaADTwlnKSAG5QEACuIEYAvlxAA
相关问题：#19437