How to get a DOM element in Stenciljs?

Question

import { Component, Prop } from '@stencil/core';
@Component({
    tag: 'my-component',
    styleUrl: 'my-component.css',
    shadow: true
})
export class MyComponent {

  @Prop() first: string;
  @Prop() last: string;
  getElementHere() {
     // how can I get the div here?
  }
  render() {
    return (
      <div>
        Hello, World! I'm {this.first} {this.last}
      </div>
    );
  }
}

I want to get the DOM element just like in native JS. How do you do this in Stencil? getElementById does not work.

Answer 1

To expand on Fernando's answer, the @Element decorator binds the component's root element to this property. It's important to note a few properties of this approach:

1. The @Element bound property is only available after the component has been loaded (componentDidLoad).
2. Because the element is a standard HTMLElement, you can access elements within your current component using the standard .querySelector(...) or .querySelectorAll(...) methods to retrieve and manipulate them.

Here is an example showing when the element is accessible, and how to manipulate nodes within this element (correct as of stencil 0.7.24):

import { Component, Element } from '@stencil/core';

@Component({
    tag: 'my-component'
})
export class MyComponent {

    @Element() private element: HTMLElement;
    private data: string[];

    constructor() {
        this.data = ['one', 'two', 'three', 'four'];
        console.log(this.element); // outputs undefined
    }

    // child elements will only exist once the component has finished loading
    componentDidLoad() {
        console.log(this.element); // outputs HTMLElement <my-component ...

        // loop over NodeList as per https://css-tricks.com/snippets/javascript/loop-queryselectorall-matches/
        const list = this.element.querySelectorAll('li.my-list');
        [].forEach.call(list, li => li.style.color = 'red');
    }

    render() {
        return (
            <div class="my-component">
                <ul class="my-list">
                    { this.data.map(count => <li>{count}</li>)}
                </ul>
            </div>
        );
    }
}

Answer 2

From the official docs

In cases where you need to get a direct reference to an element, like you would normally do with document.querySelector, you might want to use a ref in JSX.

So in your case:

import { Component, Prop } from '@stencil/core';
@Component({
    tag: 'my-component',
    styleUrl: 'my-component.css',
    shadow: true
})
export class MyComponent {

  @Prop() first: string;
  @Prop() last: string;

  divElement!: HTMLElement; // define a variable for html element

  getElementHere() {
    this.divElement  // this will refer to your <div> element
  }

  render() {
    return (
      <div ref={(el) => this.divElement= el as HTMLElement}> // add a ref here
        Hello, World! I'm {this.first} {this.last}
      </div>
    );
  }
}