Does lit-html have by any change something like React's ref feature?
For example in the following pseudo-code inputRef would be a callback function or an object { current: ... } where lit-html could pass/set the HTMLElement instance of the input element when the input element is created/attached.
// that #ref pseudo-attribute is fictional
html`<div><input #ref={inputRef}/></div>`
Thanks.
In lit-element you can use #query property decorator. It's just syntactic sugar around this.renderRoot.querySelector().
import { LitElement, html, query } from 'lit-element';
class MyElement extends LitElement {
#query('#first')
first;
render() {
return html`
<div id="first"></div>
<div id="second"></div>
`;
}
}
lit-html renders directly to the dom so you don't really need refs like you do in react, you can use querySelector to get a reference to the rendered input
Here's some sample code if you were only using lit-html
<html>
<head>
<title>lit-html example</title>
<script type="module">
import { render, html } from 'https://cdn.pika.dev/lit-html/^1.1.2';
const app = document.querySelector('.app');
const inputTemplate = label => {
return html `<label>${label}<input value="rendered input content"></label>`;
};
// rendering the template
render(inputTemplate('Some Label'), app);
// after the render we can access it normally
console.log(app.querySelector('input').value);
</script>
</head>
<body>
<div class="app"></div>
<label>
Other random input
<input value="this is not the value">
</label>
</body>
</html>
If you're using LitElement you could access to the inner elements using this.shadowRoot.querySelector if you're using shadow dom or this.querySelector if you aren't
As #WeiChing has mentioned somewhere above, since Lit version 2.0 you can use the newly added directive ref for that:
https://lit.dev/docs/templates/directives/#ref
-- [EDIT - 6th October 2021] ----------------------------
Since lit 2.0.0 has been released my answer below
is completely obsolete and unnecessary!
Please check https://lit.dev/docs/api/directives/#ref
for the right solution.
---------------------------------------------------------
Even if this is not exactly what I have asked for:
Depending on the concrete use case, one option to consider is the use of directives.
In my very special use-case it was for example (with a little luck and a some tricks) possible to simulate more or less that ref object behavior.
const inputRef = useElementRef() // { current: null, bind: (special-lit-html-directive) }
...
return html`<div><input ref=${inputRef.bind}/></div>`
In my use case I could do the following:
Before rendering, set elementRef.current to null
Make sure that elementRef.current cannot be read while the component is rerendered (elementRef.current is not needed while rendering and an exception will be thrown if someone tries to read it in render phase)
That elementRef.bind directive will fill elementRef.current with the actual DOM element if available.
After that, elementRef.current can be read again.
For lit-html v1, you can define your own custom Derivative:
import { html, render, directive } from "lit-html";
function createRef(){ return {value: null}; }
const ref = directive((refObj) => (attributePart) => {
refObj.value = attributePart.committer.element;
});
const inputRef = createRef();
render(html`<input ref=${ref(inputRef)} />`;
// inputRef.value is a reference to rendered HTMLInputElement
Related
I'm creating my custom accordion element. In which I'll have 2 components 1 for ul and other for li.
Content in file accordion-ul.ts, in which I've a slot where I want my li.
import { html, customElement, property, LitElement } from 'lit-element';
import { Accordion } from 'carbon-components';
#customElement('accordion-panel')
export default class AccordionPanel extends LitElement {
firstUpdated() {
const accordionElement = document.getElementById('accordion');
Accordion.create(accordionElement);
}
connectedCallback() {
super.connectedCallback();
}
render() {
return html`
<ul data-accordion class="accordion" id="accordion">
<slot></slot>
</ul>
`;
}
createRenderRoot() {
return this;
}
}
NOTE: I'm getting an error in the console in the firstUpdated() : Uncaught (in promise) TypeError: Cannot read property 'nodeName' of null.
The way I'm using it for testing:
<accordion-panel><li>test</li></accordion-panel>
IDK, it's not working and nothing is printing on the screen. On inspecting the element, I can see there's empty in DOM.
Your problem is that you're trying to use slots, which are a shadow DOM feature but you're not using shadow DOM (since you're overwriting the createRenderRoot method to prevent the creation of the shadowRoot)
So, if you want to use slots, just remove the createRenderRoot function from your class and use shadow DOM
Edit:
You should also update your firstUpdated method so that this part:
const accordionElement = document.getElementById('accordion');
Uses the element from your shadow DOM
const accordionElement = this.shadowRoot.querySelector('.accordion');
Then again, CarbonComponents styling will probably not work so you'll need to add those in some other way
I used to compile and insert JSX components via
<div key={ ID } dangerouslySetInnerHTML={ { __html: HTML } } />
which wrapped my HTML into a <div>:
<div>my html from the HTML object</div>
Now react > 16.2.0 has support for Fragments and I wonder if I can use that somehow to avoid wrapping my HTML in a <div> each time I get data from the back end.
Running
<Fragment key={ ID } dangerouslySetInnerHTML={ { __html: HTML } } />
will throw a warning
Warning: Invalid prop `dangerouslySetInnerHTML` supplied to `React.Fragment`. React.Fragment can only have `key` and `children` props.
in React.Fragment
Is this supported yet at all? Is there another way to solve this?
Update
Created an issue in the react repo for it if you want to upvote it.
Short Answer
Not possible:
key is the only attribute that can be passed to Fragment. In the
future, we may add support for additional attributes, such as event
handlers.
https://reactjs.org/docs/fragments.html
You may want to chime in and suggest this as a future addition.
https://github.com/facebook/react/issues
In the Meantime
You may want to consider using an HTML parsing library like:
https://github.com/remarkablemark/html-react-parser
Check out this example to see how it will accomplish your goal:
http://remarkablemark.org/blog/2016/10/07/dangerously-set-innerhtml-alternative/
In Short
You'll be able to do this:
<>
{require('html-react-parser')(
'<em>foo</em>'
)}
</>
Update December 2020
This issue (also mentioned by OP) was closed on Oct 2, 2019. - However, stemming from the original issue, it seems a RawHTML component has entered the RFC process but has not reached production, and has no set timeline for when a working solution may be available.
That being said, I would now like to allude to a solution I currently use to get around this issue.
In my case, dangerouslySetInnerHTML was utilized to render plain HTML for a user to download; it was not ideal to have additional wrapper tags included in the output.
After reading around the web and StackOverflow, it seemed most solutions mentioned using an external library like html-react-parser.
For this use-case, html-react-parser would not suffice because it converts HTML strings to React element(s). Meaning, it would strip all HTML that wasn't standard JSX.
Solution:
The code below is the no library solution I opted to use:
//HTML that will be set using dangerouslySetInnerHTML
const html = `<div>This is a div</div>`
The wrapper div within the RawHtml component is purposely named "unwanteddiv".
//Component that will return our dangerouslySetInnerHTML
//Note that we are using "unwanteddiv" as a wrapper
const RawHtml = () => {
return (
<unwanteddiv key={[]}
dangerouslySetInnerHTML={{
__html: html,
}}
/>
);
};
For the purpose of this example, we will use renderToStaticMarkup.
const staticHtml = ReactDomServer.renderToStaticMarkup(
<RawHtml/>
);
The ParseStaticHtml function is where the magic happens, here you will see why we named the wrapper div "unwanteddiv".
//The ParseStaticHtml function will check the staticHtml
//If the staticHtml type is 'string'
//We will remove "<unwanteddiv/>" leaving us with only the desired output
const ParseStaticHtml = (html) => {
if (typeof html === 'string') {
return html.replace(/<unwanteddiv>/g, '').replace(/<\/unwanteddiv>/g, '');
} else {
return html;
}
};
Now, if we pass the staticHtml through the ParseStaticHtml function you will see the desired output without the additional wrapper div:
console.log(ParseStaticHtml(staticHtml));
Additionally, I have created a codesandbox example that shows this in action.
Notice, the console log will throw a warning: "The tag <unwanteddiv> is unrecognized in this browser..." - However, this is fine because we intentionally gave it a unique name so we can easily differentiate and target the wrapper with our replace method and essentially remove it before output.
Besides, receiving a mild scolding from a code linter is not as bad as adding more dependencies for something that should be more simply implemented.
i found a workaround
by using react's ref
import React, { FC, useEffect, useRef } from 'react'
interface RawHtmlProps {
html: string
}
const RawHtml: FC<RawHtmlProps> = ({ html }) => {
const ref = useRef<HTMLDivElement>(null)
useEffect(() => {
if (!ref.current) return
// make a js fragment element
const fragment = document.createDocumentFragment()
// move every child from our div to new fragment
while (ref.current.childNodes[0]) {
fragment.appendChild(ref.current.childNodes[0])
}
// and after all replace the div with fragment
ref.current.replaceWith(fragment)
}, [ref])
return <div ref={ref} dangerouslySetInnerHTML={{ __html: html }}></div>
}
export { RawHtml }
Here's a solution that works for <td> elements only:
type DangerousHtml = {__html:string}
function isHtml(x: any): x is DangerousHtml {
if(!x) return false;
if(typeof x !== 'object') return false;
const keys = Object.keys(x)
if(keys.length !== 1) return false;
return keys[0] === '__html'
}
const DangerousTD = forwardRef<HTMLTableCellElement,Override<React.ComponentPropsWithoutRef<'td'>,{children: ReactNode|DangerousHtml}>>(({children,...props}, ref) => {
if(isHtml(children)) {
return <td dangerouslySetInnerHTML={children} {...props} ref={ref}/>
}
return <td {...props} ref={ref}>{children}</td>
})
With a bit of work you can make this more generic, but that should give the general idea.
Usage:
<DangerousTD>{{__html: "<span>foo</span>"}}</DangerousTD>
I have a styled component:
const StyledComponent = styled.div`
...
`;
and I want to focus it when the component that uses it is mounted:
class someComponent extends React.Component {
componentDidMount() {
this.sc.focus();
}
render() {
return (
<StyledComponent innerRef={(elem) => { this.sc = elem; }}>
...
</StyledComponent>
);
}
}
this technique does not work - is there a solution for this?
You can't focus non-interactive elements without the use of tabIndex ("tabindex" in normal HTML). The "div" element is considered non-interactive (unlike anchor links "a" and button controls "button".)
If you want to be able to focus this element, you'll need to add a tabIndex prop. You can use .attrs if desired to have it be added automatically so you don't need to write the prop every time.
This link
has an example with both React 16 React.createRef() and the callback method.
Have you tried setting the autoFocus attribute, or is that not fit for your use case?
Try passing the autoFocus prop to your StyledComponent like <StyledComponent autoFocus />.
I want to render the pure HTML coming from some external source into react component. I saw few solutions where people are talking about some conversion tools (HTML to JSX) but I want to handle everything in my component so while mounting it will get the HTML response and that needs to render.
You can use dangerouslySetInnerHTML for this:
function createMarkup() { return {__html: 'First ยท Second'}; };
<div dangerouslySetInnerHTML={createMarkup()} />
But as the method name suggests: you should be very sure of what you are doing there and the security implications it has.
This shouldn't be difficult to do . Assign your HTML to a div and then render it using {variable name} JSX allows you to do this and with ES6 integration you can also use class instead of className.
var Hello = React.createClass({
render: function() {
var htmlDiv = <div>How are you</div>
return <div>Hello {this.props.name}
{htmlDiv}
</div>;
}
});
ReactDOM.render(
<Hello name="World" />,
document.getElementById('container')
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.14.8/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.14.8/react-dom.min.js"></script>
<div id="container">
<!-- This element's contents will be replaced with your component. -->
</div>
Is it possible to publish new Polymer component attributes at runtime?
<polymer-element name="dynamic-attributes">
<template></template>
<script>
Polymer('dynamic-attributes', {
ready: function(){
var attributes = new Thing().getAttributes();
this.publishAttributes(attributes); // imaginary method
},
});
</script>
</polymer-element>
More info...
I'm writing a component lib that wraps Seriously.js.
Here is an example of the ideal implementation.
<seriously-graph linear>
<seriously-source>
<img src="images/pencils.jpg">
</seriously-source>
<seriously-effect type="pixelate" pixelSize="{{pixelSize}}"></seriously-effect>
<seriously-effect type="blur" amount=".5"></seriously-effect>
<seriously-target width="411" height="425"></seriously-target>
</seriously-graph>
I have a work-around that uses MutationObserver to detect attribute changes. It works, but then I have to find a solution for serialization and make property getters/setters. It feels like I'm re-inventing the wheel (Polymer), and was hoping there was a built-in method of doing this.
Here's a Gist that does what you're looking for. Basically, it dynamically creates a concrete <polymer-element> for an effect the first time it's used, and then swaps the generic instance with a dynamically created concrete one, copying any binding declarations in the process. The source would be:
<seriously-effect type="blur" amount="{{someAmount}}"></seriously-effect>
But with Inspect Element, you'd see:
<seriously-effect-blur amount="{{someAmount}}"></seriously-effect-blur>
Yes, it is possible by assigning an attributes object to publish node. See https://www.polymer-project.org/docs/polymer/polymer.html#attributes for details.
Your method must return an object of attributes:
Polymer('dynamic-attributes', {
publish: (new Thing()).getAttributes() || {}
});
Maybe you could make a global array and use it as attribute?
<polymer-element name="app-globals" attributes="values">
<script>
(function() {
var values = {};
Polymer({
ready: function() {
this.values = values;
for (var i = 0; i < this.attributes.length; ++i) {
var attr = this.attributes[i];
values[attr.nodeName] = attr.value;
}
}
});
})();
</script>
</polymer-element>
<app-globals id='myDynamicFunctions' someFunction someOtherFunction></app-globals>
<script>
//then define it
document.$.myDynamicFunctions.values.someFunction = function(){...}
</script>
I am not quite sure what you are looking for, this might give you a hint...