Using jQuery and bootstrap JS with stenciljs components

Question

We have application that is built using Angular and now for all customer-specific requirements we want to build web components using stencil js.

Idea is to keep core application clean and not to mixin code for specific client requirements.

So we came up to web components and we stick to Stencil JS.

First problem that we are facing is that our web component will need to use jquery, bootstrap js and some third party js as well.

We want to build our components to be encapsulated from outside that means they will be in shadow dom.

Now I have two questions

1) Is it good practice that every component include JS libraries like jQuery, bootstrap js etc because it doesn't sound to me as a good idea 2) How we can include jQuery for example into web component.

I tried many ways and the last one was to include tag in the constructor of a stencil web component, but it doesn't work.

export class TestComponent {

  @Prop() token: string;

  @State() test: string;
  @Element() private element: HTMLElement;

  constructor() {

    this.element.innerHTML = `
    <script src="../../assets/js/jquery.min.js"></script>

`;

So the question is how to use JS third party libraries in web component built in stencil that is in shadow dom ( shadow option is set to true )

Any opinions about this in general are welcome and will be appreciated :)

Christian Meyer · Accepted Answer · 2019-10-26T21:19:13.997

For me it sounds like you are bending the purpose of Stencil and Web-components a bit. I never had this pain doing this but to answer your question: It depends of what you wanna achieve. For example you can use Jquery natively inside the shadow-dom when you import Jquery in the Light-dom.

Index.html

<script src="/jquery.min.js"></script>
</head>
<body>
  <my-component></my-component>
  <div id="test2"></div>
</body>

my-component.tsx

  testfunc(){
    console.log($().jquery);
    console.log($("#test"));
    console.log($("#test2"));
  }
  render() {
    return <div id="test">
            <button onclick={this.testfunc.bind(this)}>asd</button>
           </div>;
  }

The result of testfunc are here:

So as you can see - you already can use Jquery just by putting it into your main application. But there are some limitations as you can see you have access to all the DOM elements from light-dom but none from shadow-dom. Thats why #test wasn't found and #test2 was.

But interesting to mention here is that I was also able to load a file inside this #test2 div container which is in the index.html. Just by using the jquery .load function from inside the web-component.

$( "#test2" ).load( "/index.html" );

Things get a bit more complicated when you want to use the $ selector to get elements inside the web-component (shadow-dom) but there is absolutely no reason to do so: Stencil has it's own this.el.shadowRoot.querySelector() that you can use inside the component or you can directly stick a variable to a DOM element like so:

  render() {
    return <div ref={el => this.element = el}>
            <button onclick={this.testfunc.bind(this)}>Press Button</button>
           </div>;
  }

Than you can use this.element inside the web-component to access the div. But in general you can also try to use the scoped flag in the component decorator. Than you usually can use everything from the light dom because there is not such a hard isolation:

    @Component({
  tag: 'my-component',
  styleUrl: 'my-component.css',
  shadow: true ---> instead of this
  scoped: true ---> try this
})

To summarize a bit: I think there is never a good reason to use these libraries inside a web-component in general. But if you really have to - it always depends on your needs and what you want / need to achieve. Stencil has some really helpful and good built in functions.

I also wrote a little comment of how i use Stenciljs in this context and what i would do instead. — Christian Meyer, Oct 26 '19 at 21:49

score 1 · Answer 2 · answered Oct 26 '19 at 20:38

For most web components I would not use jQuery, as with any modern framework dom manipulation is not needed, mostly you just focus on render function.

I did a test and this seems to work ok after adding jquery dependency with npm i jquery:

import { Component, h } from '@stencil/core';
import $ from "jquery";

@Component({
    tag: 'app-test'
})
export class AppTest {  
    render() {
        const version = $().jquery;
        return [
            <div>
                jQuery Version: {version}
            </div>
        ];
    }
}

score 0 · Answer 3 · answered Oct 26 '19 at 21:48

I would consider using Stencil exactly the opposite way. Create your generic stuff in Stencil and than the customer specific inside Angular. For example you start with a simple "button" as a web-component in stencil.

export class CoolestButton {
      render() {
        return <button class="coolest-button"></button>
      }
}

Than you create another web-component "dropdown" which uses the "button" as foundation.

export class CoolestDropdown {
      ...
       someDropdownFunctions(){}
      ...
      render() {
        ...
        return [<coolest-button></coolest-button>, ...dropdownSpecific]
      }
}

Than you create a Header component which exists of dropdowns.

export class CoolestHeader {
      render() {
        return [
<coolest-dropdown data="NavPoint1,NavPoint2,NavPoint3">Home</coolest-dropdown>, 
<coolest-dropdown data="About-us,Impress">Home</coolest-dropdown>
];
      }

The amazing thing of Stencil is that you can use 10000x times the coolest-button but it will only will load it once. Thats why nesting the web-components like this is absolutely coding sugar. Than you have a really strong library that you can use in all your customer projects. And when you write your tests - every customer application is tested too since they have all the same base.

score 0 · Answer 4 · answered Aug 08 '21 at 08:23

jQuery can be used inside a Shadow DOM with out any issues using stenciljs.

If the jQuery has already been added to the light DOM or not has to be checked inside the web component. In some cases when we load the jQuery again it resets the events in the light DOM creating issues in Light DOM. You can use a console.log($) and try and catch to check if its loaded other wise load.

$ will also work if you install 'types' for jQuery.

So basically it only matters if the external libraries tries to access the DOM using

document.getElementById

inside the library files.

Inside shadow DOM

this.el.shadowroot

has to be used. The associated css should be added inside the webcomponent as well.

Using jQuery and bootstrap JS with stenciljs components

4 Answers4