[英]WebComponents: Firefox custom-element is not showing
我正在使用Web組件的“自定義元素”功能,並且需要支持舊的瀏覽器(Firefox v60),因此與其通過webcomponent-loader.js加載所有polyfill來加載polyfill。 基於特征檢測的延遲加載的custom-elementpolyfill
(function() { if(!window.customElements){ var ce = document.createElement('script'); ce.type = 'text/javascript'; ce.async = true; ce.src = 'https://unpkg.com/@webcomponents/custom-elements@1.2.4/custom-elements.min.js'; /** * loading "customElement" polyfills wont't fire "WebComponentsReady" event, it will be called when we use * "webcomponent-loader.js" but it will load other polyfills("shadow-dom"), so loading the "customElements" polyfill alone * based on feature detection and firing "WebComponentsReady" event manually. */ ce.onload = function() { document.dispatchEvent( new CustomEvent('WebComponentsReady', {bubbles: true})); }; var st = document.getElementsByTagName('script')[0]; st.parentNode.insertBefore(ce, st); } })()
並在加載時手動觸發了WebComponentsReady
事件。 注冊了如下元素
let registerElement = () => { if(!window.customElements.get(“wc-button")){ window.customElements.define('wc-button', WCButton); } }; if(window.customElements){ registerElement(); } else { document.addEventListener('WebComponentsReady', registerElement); }
WebComponentsReadygot已觸發,並且已在偵聽器回調中被調用以定義/注冊該元素,但是該元素未在firefox60.6.1esr(64位)的頁面中顯示或加載。
webcomponents-loader.js為您執行功能檢測,而不是等待WebComponentsReady事件,而是執行
<script src="https://unpkg.com/@webcomponents/webcomponentsjs/webcomponents-loader.js"></script>
<script>
window.WebComponents.waitFor(() => {
// do stuff that needs the polyfill
})
</script>
欲獲得更多信息:
僅當實現了自定義元素時,HTMLElement才能擴展(可以在本地使用polyfill進行擴展)。
因此,只有在加載polyfill之后,才必須定義<wc-button>
自定義元素類。
在您的示例中:
let registerElement = () => {
if(!window.customElements.get("wc-button")){
//define the WCButton class here
class WCButton extends HTMLElement {
//...
}
window.customElements.define(‘wc-button', WCButton);
}
};
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.