Node.isConnected

The isConnected read-only property of the Node interface returns a boolean indicating whether the Node is connected (directly or indirectly) to the context object, for example the Document object in the case of the normal DOM, or the ShadowRoot (en-US) in the case of a shadow DOM.

Синтаксис

var isItConnected = nodeObjectInstance.isConnected

Return value

A Boolean (en-US) that is true if the node is connected to its relevant context object, and false if not.

Пример

Стандартный DOM пример:

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

A shadow DOM example:

// 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

Спецификация

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

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