TypeScript常见类型错误 | 类型EventTarget上不存在属性 - ts中的dom类型

TypeScript常见类型错误 | 类型EventTarget上不存在属性

报错描述

在TypeScript中，使用事件回调函数的参数event.target.xxx时，发生报错：类型'EventTarget上不存在属性'className'

//ts并不清楚鼠标点击的位置`event.target`是什么类型
const name = (event.target as HTMLElement).className
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event对象的类型为Event，Event接口表示一个DOM事件,包含了事件的基本信息,如事件类型、目标元素等。可以使用该接口来定义事件的类型。

解决办法

1.显示指定为dom类型

显示的指定event.target的类型

//方法1
const name = (event.target as HTMLElement).className
//方法2
const name = (<HTMLElement>event.target).className
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2.更改event的类型

type HTMLElementEvent<T extends HTMLElement> = Event & {
  target: T
}

function handleClick(event: HTMLElementEvent<HTMLElement>) {
  const name = event.target.className
}
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类型解析

• Element 是所有Document对象元素的基类，只包含一些基本属性和方法。
• HTMLElement 是 HTML 文档中某个元素的具体类型，该类型包含了所有 HTML 元素的共有属性和方法。

DOM类型的声明

更具体的dom元素类型基本都继承HTMLElement，并对其进行了扩充。如果报错到xxx不存在xx类型，可以将其进行更具体化的约束。

interface HTMLElementTagNameMap {
    "a": HTMLAnchorElement;
    "abbr": HTMLElement;
    "address": HTMLElement;
    "applet": HTMLAppletElement;
    "area": HTMLAreaElement;
    "article": HTMLElement;
    "aside": HTMLElement;
    "audio": HTMLAudioElement;
    "b": HTMLElement;
    "base": HTMLBaseElement;
    "basefont": HTMLBaseFontElement;
    "bdi": HTMLElement;
    "bdo": HTMLElement;
    "blockquote": HTMLQuoteElement;
    "body": HTMLBodyElement;
    "br": HTMLBRElement;
    "button": HTMLButtonElement;
    "canvas": HTMLCanvasElement;
    "caption": HTMLTableCaptionElement;
    "cite": HTMLElement;
    "code": HTMLElement;
    "col": HTMLTableColElement;
    "colgroup": HTMLTableColElement;
    "data": HTMLDataElement;
    "datalist": HTMLDataListElement;
    "dd": HTMLElement;
    "del": HTMLModElement;
    "details": HTMLDetailsElement;
    "dfn": HTMLElement;
    "dialog": HTMLDialogElement;
    "dir": HTMLDirectoryElement;
    "div": HTMLDivElement;
    "dl": HTMLDListElement;
    "dt": HTMLElement;
    "em": HTMLElement;
    "embed": HTMLEmbedElement;
    "fieldset": HTMLFieldSetElement;
    "figcaption": HTMLElement;
    "figure": HTMLElement;
    "font": HTMLFontElement;
    "footer": HTMLElement;
    "form": HTMLFormElement;
    "frame": HTMLFrameElement;
    "frameset": HTMLFrameSetElement;
    "h1": HTMLHeadingElement;
    "h2": HTMLHeadingElement;
    "h3": HTMLHeadingElement;
    "h4": HTMLHeadingElement;
    "h5": HTMLHeadingElement;
    "h6": HTMLHeadingElement;
    "head": HTMLHeadElement;
    "header": HTMLElement;
    "hgroup": HTMLElement;
    "hr": HTMLHRElement;
    "html": HTMLHtmlElement;
    "i": HTMLElement;
    "iframe": HTMLIFrameElement;
    "img": HTMLImageElement;
    "input": HTMLInputElement;
    "ins": HTMLModElement;
    "kbd": HTMLElement;
    "label": HTMLLabelElement;
    "legend": HTMLLegendElement;
    "li": HTMLLIElement;
    "link": HTMLLinkElement;
    "main": HTMLElement;
    "map": HTMLMapElement;
    "mark": HTMLElement;
    "marquee": HTMLMarqueeElement;
    "menu": HTMLMenuElement;
    "meta": HTMLMetaElement;
    "meter": HTMLMeterElement;
    "nav": HTMLElement;
    "noscript": HTMLElement;
    "object": HTMLObjectElement;
    "ol": HTMLOListElement;
    "optgroup": HTMLOptGroupElement;
    "option": HTMLOptionElement;
    "output": HTMLOutputElement;
    "p": HTMLParagraphElement;
    "param": HTMLParamElement;
    "picture": HTMLPictureElement;
    "pre": HTMLPreElement;
    "progress": HTMLProgressElement;
    "q": HTMLQuoteElement;
    "rp": HTMLElement;
    "rt": HTMLElement;
    "ruby": HTMLElement;
    "s": HTMLElement;
    "samp": HTMLElement;
    "script": HTMLScriptElement;
    "section": HTMLElement;
    "select": HTMLSelectElement;
    "slot": HTMLSlotElement;
    "small": HTMLElement;
    "source": HTMLSourceElement;
    "span": HTMLSpanElement;
    "strong": HTMLElement;
    "style": HTMLStyleElement;
    "sub": HTMLElement;
    "summary": HTMLElement;
    "sup": HTMLElement;
    "table": HTMLTableElement;
    "tbody": HTMLTableSectionElement;
    "td": HTMLTableDataCellElement;
    "template": HTMLTemplateElement;
    "textarea": HTMLTextAreaElement;
    "tfoot": HTMLTableSectionElement;
    "th": HTMLTableHeaderCellElement;
    "thead": HTMLTableSectionElement;
    "time": HTMLTimeElement;
    "title": HTMLTitleElement;
    "tr": HTMLTableRowElement;
    "track": HTMLTrackElement;
    "u": HTMLElement;
    "ul": HTMLUListElement;
    "var": HTMLElement;
    "video": HTMLVideoElement;
    "wbr": HTMLElement;
}
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常见事件类型的声明

    interface GlobalEventHandlersEventMap {
        "abort": UIEvent;
        "animationcancel": AnimationEvent;
        "animationend": AnimationEvent;
        "animationiteration": AnimationEvent;
        "animationstart": AnimationEvent;
        "auxclick": MouseEvent;
        "beforeinput": InputEvent;
        "blur": FocusEvent;
        "cancel": Event;
        "canplay": Event;
        "canplaythrough": Event;
        "change": Event;
        "click": MouseEvent;
        "close": Event;
        "compositionend": CompositionEvent;
        "compositionstart": CompositionEvent;
        "compositionupdate": CompositionEvent;
        "contextmenu": MouseEvent;
        "copy": ClipboardEvent;
        "cuechange": Event;
        "cut": ClipboardEvent;
        "dblclick": MouseEvent;
        "drag": DragEvent;
        "dragend": DragEvent;
        "dragenter": DragEvent;
        "dragleave": DragEvent;
        "dragover": DragEvent;
        "dragstart": DragEvent;
        "drop": DragEvent;
        "durationchange": Event;
        "emptied": Event;
        "ended": Event;
        "error": ErrorEvent;
        "focus": FocusEvent;
        "focusin": FocusEvent;
        "focusout": FocusEvent;
        "formdata": FormDataEvent;
        "gotpointercapture": PointerEvent;
        "input": Event;
        "invalid": Event;
        "keydown": KeyboardEvent;
        "keypress": KeyboardEvent;
        "keyup": KeyboardEvent;
        "load": Event;
        "loadeddata": Event;
        "loadedmetadata": Event;
        "loadstart": Event;
        "lostpointercapture": PointerEvent;
        "mousedown": MouseEvent;
        "mouseenter": MouseEvent;
        "mouseleave": MouseEvent;
        "mousemove": MouseEvent;
        "mouseout": MouseEvent;
        "mouseover": MouseEvent;
        "mouseup": MouseEvent;
        "paste": ClipboardEvent;
        "pause": Event;
        "play": Event;
        "playing": Event;
        "pointercancel": PointerEvent;
        "pointerdown": PointerEvent;
        "pointerenter": PointerEvent;
        "pointerleave": PointerEvent;
        "pointermove": PointerEvent;
        "pointerout": PointerEvent;
        "pointerover": PointerEvent;
        "pointerup": PointerEvent;
        "progress": ProgressEvent;
        "ratechange": Event;
        "reset": Event;
        "resize": UIEvent;
        "scroll": Event;
        "scrollend": Event;
        "securitypolicyviolation": SecurityPolicyViolationEvent;
        "seeked": Event;
        "seeking": Event;
        "select": Event;
        "selectionchange": Event;
        "selectstart": Event;
        "slotchange": Event;
        "stalled": Event;
        "submit": SubmitEvent;
        "suspend": Event;
        "timeupdate": Event;
        "toggle": Event;
        "touchcancel": TouchEvent;
        "touchend": TouchEvent;
        "touchmove": TouchEvent;
        "touchstart": TouchEvent;
        "transitioncancel": TransitionEvent;
        "transitionend": TransitionEvent;
        "transitionrun": TransitionEvent;
        "transitionstart": TransitionEvent;
        "volumechange": Event;
        "waiting": Event;
        "webkitanimationend": Event;
        "webkitanimationiteration": Event;
        "webkitanimationstart": Event;
        "webkittransitionend": Event;
        "wheel": WheelEvent;
    }
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