Node.isConnected

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

isConnected 是 Node 的一个只读属性接口。无论节点是否与 DOM 树连接，该属性都会返回一个布尔值 (en-US)。例如：Document 对象与一般 DOM 树连接，ShadowRoot 与 shadow DOM 连接。

语法

var isItConnected = nodeObjectInstance.isConnected

返回值

返回 布尔值 (en-US) — 如果该节点与 DOM 树连接则返回 true, 否则返回 false。

样例

标准 DOM 树

let test = document.createElement("p");
console.log(test.isConnected); // Returns false
document.body.appendChild(test);
console.log(test.isConnected); // Returns true

Shadow DOM 树

// Create a shadow root
var shadow = this.attachShadow({ mode: "open" });

// Create some CSS to apply to the shadow dom
var style = document.createElement("style");
console.log(style.isConnected); // returns false

style.textContent =
  ".wrapper {" +
  "position: relative;" +
  "}" +
  ".info {" +
  "font-size: 0.8rem;" +
  "width: 200px;" +
  "display: inline-block;" +
  "border: 1px solid black;" +
  "padding: 10px;" +
  "background: white;" +
  "border-radius: 10px;" +
  "opacity: 0;" +
  "transition: 0.6s all;" +
  "position: absolute;" +
  "bottom: 20px;" +
  "left: 10px;" +
  "z-index: 3;" +
  "}" +
  // Attach the created style element to the shadow dom

  shadow.appendChild(style);
console.log(style.isConnected); // Returns true

规范

Specification
DOM Standard # ref-for-dom-node-isconnected①

浏览器兼容性

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