connect(props)

Calling connect will initialize and render an element and call its connected hook. Normally this is called by the connectedCallback, but can be called manually for testing:

import { StacheElement } from "can/everything";

class MyElement extends StacheElement {
    static view = `
        <p>{{this.age}}</p>
    `;
    static props = {
        age: { type: Number, default: 30 }
    };
    connected() {
        const p = document.createElement("p");
        p.innerHTML = "World";
        this.appendChild(p);
    }
}
customElements.define("my-el", MyElement);

const myEl = new MyElement()
    .connect({ greeting: "Hi" });

myEl.greeting  // -> Hi
myEl.innerHTML // -> <p>Hi</p>
               //    <p>World</p>