@popeindustries/lit-html-server
Advanced tools
Render lit-html templates on the server as Node.js streams. Supports all lit-html types, special attribute expressions, and most of the standard directives.
Although based on lit-html semantics, lit-html-server is a great general purpose HTML template streaming library. Tagged template literals are a native JavaScript feature, and the HTML rendered is 100% standard markup, with no special syntax or client-side runtime required.
Install with npm/yarn:
$ npm install --save @popeindustries/lit-html-server
...write your lit-html template:
const { html } = require('@popeindustries/lit-html-server');
function layout(data) {
return html`<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>${data.title}</title>
</head>
<body>
${body(data.api)}
</body>
</html>`;
}
async function body(apiPath) {
// Some Promise-based request method
const data = await fetchRemoteData(apiPath);
return html`<h1>${data.title}</h1>
<x-widget ?enabled=${data.hasWidget}></x-widget>
<p class="${data.invertedText ? 'negative' : ''}">${data.text}</p>`;
}
...and render:
const { render } = require('@popeindustries/lit-html-server');
// Returns a Node.js Readable stream which can be piped to `response`
render(layout({ title: 'Home', api: '/api/home' }));
htmlThe tag function to apply to HTML template literals (also aliased as svg)
const name = 'Bob';
html`<h1>Hello ${name}!</h1>`;
All template expressions (values interpolated with ${value}) are escaped for securely including in HTML by default. An unsafe-html directive is available to disable escaping:
const { unsafeHTML } = require('@popeindustries/lit-html-server/directives/unsafe-html.js');
html`<div>
${unsafeHTML('<span>dangerous!</span>')}
</div>`;
render(template: string|Readable): ReadableReturns the result of the template tagged by html as a Node.js Readable stream of markup.
render(html`<h1>Hello ${name}!</h1>`).pipe(response);
renderToString(template: string|Readable): Promise<string>Returns the result of the template tagged by html as a Promise which resolves to a string of markup.
const markup = await renderToString(html`<h1>Hello ${name}!</h1>`);
lit-html-server can also be used in a browser context:
const { html, renderToString } = require('@popeindustries/lit-html-server/browser.js');
htmlThe tag function to apply to HTML template literals (also aliased as svg). See above.
renderToString(template: string|Promise): Promise<string>Returns the result of the template tagged by html as a Promise which resolves to a string of markup. See above.
In general, all of the standard lit-html rules and semantics apply when rendering templates on the server with lit-html-server (read more about lit-html and writing templates here).
Although there are no technical restrictions for doing so, if you plan on writing templates for use on both the server and client, you should abide by the same rules:
All of the lit-html expression syntax is supported:
html`<h1>Hello ${name}</h1>`;
//=> <h1>Hello Bob</h1>
html`<div id=${id}></div>`;
//=> <div id="main"></div>
html`<input type="checkbox" ?checked=${checked}>`;
//=> <input type="checkbox" checked> if truthy
//=> <input type="checkbox" > if falsey
html`<input .value=${value}>`;
//=> <input >
const fn = (e) => console.log('clicked');
html`<button @click=${fn}>Click Me</button>`;
//=> <button >Click Me</button>
Most of the lit-html value types are supported:
primitives: String, Number, Boolean, null, and undefined
note that
undefinedhandling is the same as in lit-html: stringified when used as an attribute value, and ignored when used as a node value
nested templates:
const header = html`<h1>Header</h1>`;
const page = html`
${header}
<p>This is some text</p>
`;
const items = [1, 2, 3];
html`<ul>${items.map((item) => html`<li>${item}</li>`)}</ul>`;
html`<p>total = ${new Set(items)}</p>`;
const promise = fetch('sample.txt').then((r) => r.text());
html`<p>The response is ${promise}.</p>`;
Most of the built-in lit-html directives are also included for compatibility when using templates on the server and client (even though some directives are no-ops in a server context):
guard(expression, valueFn): no-op since re-rendering does not apply (renders result of valueFn)const guard = require('@popeindustries/lit-html-server/directives/guard.js');
html`<div>
${guard(items, () => items.map((item) => html`${item}`))}
</div>`;
ifDefined(value): sets the attribute if the value is defined and removes the attribute if the value is undefinedconst ifDefined = require('@popeindustries/lit-html-server/directives/if-defined.js');
html`<div class=${ifDefined(className)}></div>`;
repeat(items, keyfn, template)): no-op since re-rendering does not apply (maps items over template)const repeat = require('@popeindustries/lit-html-server/directives/repeat.js');
html`<ul>
${repeat(items, (i) => i.id, (i, index) => html`<li>${index}: ${i.name}</li>`)}
</ul>`;
until(promise, defaultContent): no-op since only one render pass (renders defaultContent)const until = require('@popeindustries/lit-html-server/directives/until.js');
html`<p>
${until(fetch('content.txt').then((r) => r.text()), html`<span>Loading...</span>`)}
</p>`;
when(condition, trueTemplate, falseTemplate): switches between two templates based on the given condition (does not cache templates)const when = require('@popeindustries/lit-html-server/directives/when.js');
html`<p>
${when(checked, () => html`Checkmark is checked`, () => html`Checkmark is not checked`)}
</p>`;
classMap(classInfo): applies css classes to the class attribute. 'classInfo' keys are added as class names if values are truthyconst classMap = require('@popeindustries/lit-html-server/directives/classMap.js');
html`<div class=${classMap({ red: true })}></div>`;
styleMap(styleInfo): applies css properties to the style attribute. 'styleInfo' keys and values are added as style propertiesconst styleMap = require('@popeindustries/lit-html-server/directives/styleMap.js');
html`<div style=${styleMap({ color: 'red' })}></div>`;
Thanks to Thomas Parslow for the stream-template library that was the basis for this streaming implementation, and thanks to Justin Fagnani and the team behind the lit-html project!
FAQs
Efficiently render streaming lit-html templates on the server (or in a ServiceWorker!)
The npm package @popeindustries/lit-html-server receives a total of 1,821 weekly downloads. As such, @popeindustries/lit-html-server popularity was classified as popular.
We found that @popeindustries/lit-html-server demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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