闭包是由捆绑起来(封闭的)的函数和函数周围状态(词法环境)的引用组合而成。换言之,闭包让函数能访问它的外部作用域。在 JavaScript 中,闭包会随着函数的创建而同时创建。 词法作用域 注意下面的示例代码: jsCopy to Clipboard function init() { var name = "Mozilla"; // name 是 init 创建的局部变量 functi...
类构造函数总是通过 new 调用,所以它们的行为与构造函数相同:this 值是正在创建的新实例。类方法的行为像对象字面量中的方法——this 值是方法被访问的对象。如果方法没有转移到另一个对象,this 通常是类的一个实例。 静态方法不是 this 的属性。它们是类本身的属性。因此,它们通常在类上访问,this 是类(或子...
The DOM tree includes elements such as and , among many others. It provides functionality globally to the document, like how to obtain the page's URL and create new elements in the document.EventTarget Node Document The Document interface describes the common properties and methods for any...
In development. Supported in a pre-release version. In development. Supported in a pre-release version. No support No support Deprecated. Not for use in new websites. See implementation notes. Requires a vendor prefix or different name for use. Has more compatibility info. ...
new URL('/en-US/docs', "https://developer.mozilla.org/fr-FR/toto"); // Creates a URL pointing to 'https://developer.mozilla.org/en-US/docs' var h = new URL('/en-US/docs', a); // Creates a URL pointing to 'https://developer.mozilla.org/en-US/docs' var i = new URL('...
("image1x.png" 1x, "image2x.png" 2x); /* speech output: alternative text after a "/" */ content: url("../img/test.png") / "This is the alt text"; /* <string> value */ content: "unparsed text"; /* <counter> values, optionally with <list-style-type> */ content: ...
getElementById("myAnchor"); const queryString = anchor.search; // Returns:'?q=123' // Further parsing: const params = new URLSearchParams(queryString); const q = parseInt(params.get("q")); // is the number 123 Specifications Specification HTML # dom-location-search-dev...
// with `^` in pathname const pattern = new URLPattern({ pathname: "(^b)" }); console.log(pattern.test("https://example.com/ba")); // false console.log(pattern.test("https://example.com/xa")); // false jsCopy to Clipboard // with `^` in protocol const pattern = new URL...
querySelector("video"); const assetURL = "frag_bunny.mp4"; // Need to be specific for Blink regarding codecs const mimeCodec = 'video/mp4; codecs="avc1.42E01E, mp4a.40.2"'; function loadVideo() { if (MediaSource.isTypeSupported(mimeCodec)) { const mediaSource = new MediaSource()...
Trigger builds of documents that haven't been built, by URL. Linting All JavaScript and TypeScript code needs to be formatted withprettierand it's easy to test this with: yarn prettier-check And conveniently, if you're not even interested in what the flaws were, run: ...