Deval Desai

Deval Desai

1572250985

Render HTML with Vanilla JavaScript and lit-html

Sometimes you need to render HTML elements on a web page. And like Goldilocks’ search for “just right”, you have to try a few techniques before you find the right one. Using a framework may be too hard. Using pure HTML and the DOM API may be too soft. What you need is something in the middle that is just right. Is lit-html “just right”? Let’s find out.

First, I’ll show how this all works. Then at the end of this article, I’ll explain everything you need to get started with lit-html to try this for yourself.

When you’re done, you can push your HTML app with lit-html to the cloud to see it in all of its glory! I included a link to a free Azure trial, so you can try it yourself.

Resources:

The Sample App

Here is the app I’ll demonstrate in this article. It fetches a list of heroes and renders them when you click the button. It also renders a progress indicator while it is fetching.

Tour of Heroes

What’s the Value of lit-html

When you focus on rendering content, and nothing else, lit-html is a good fit. It works closely with the DOM to render content, and refresh it in an optimal manner. The docs can provide you with more details, but the basic code for lit-html looks like this.

// Credit: As seen in official docs https://lit-html.polymer-project.org/guide/getting-started

// Import lit-html
import { html, render } from 'lit-html';

// Define a template
const myTemplate = name =>
  html`
    <p>Hello ${name}</p>
  `;

// Render the template to the document
render(myTemplate('World'), document.body);

You import lit-html, define a template, then render it to the DOM. That’s it!

Rendering HTML

A progress bar is fairly basic. There is some HTML, and we show it when needed and hide it when it is not required. While we could use a template, or innerHTML, or the DOM API for this, let’s see what this would look like with lit-html.

First, we get a reference to the element in the DOM where the progress bar will appear.

Then we define the template. This code looks and feels like JSX (or TSX). The advantage here is that you can write the HTML. You wrap the HTML in a template string (notice the back-tick character is used and not a single quote). Template strings allow you to span lines and insert variables where needed (we’ll see this soon). The magic that makes this work is the html tag that precedes the template string. The html tag is what tells lit-html that you are about to define a template.

Next, we compile the template and pass those results to lit-html’s render function, which places the results in the DOM. Finally, we hide or show the progress bar as needed.

function showProgress(show = true) {
  const container = document.getElementById('progress-placeholder');

  const template: () => TemplateResult = () => html`
    <progress class="progress is-medium is-info" max="100"></progress>
  `;
  const result = template();
  render(result, container);

  container.style.display = show ? 'block' : 'none';
}

Now you can run this showProgress function any time you want to show the progress bar.

Note that when a template is re-rendered, the only part that is updated is the data that changed. If no data changed, nothing is updated.

Rendering HTML with Dynamic Values

The progress bar does not change each time it is rendered. You will have situations where you want your HTML to change. For example, you may have a message area on your web app that shows a styled message box with a title and a message. The title and message will change every time you show the message area. Now you have dynamic values.

The HTML is defined with a template string, so it is trivial to add a variable into it. Notice the code below adds a title and text into the template, using the ${data.title} and ${data.text} syntax, respectively.

Then the template is compiled and rendered were needed.

When this template is re-rendered, the only part that is updated is the data that changed. In this case, that’s the title and text.

function showMessage(text: string, title = 'Info') {
  const template: (data: any) => TemplateResult = (data: Message) => html`
    <div id="message-box" class="message is-info">
      <h3 class="message-header">${data.title}</h3>
      <p class="message-body">${data.text}</p>
    </div>
  `;

  const el = document.getElementById('message-placeholder');
  const result = template({ title, text });
  render(result, el);

  el.style.visibility = !!text ? 'visible' : 'hidden';
}

Rendering a List

Things get a little more real when we render a list. Let’s think about that for a moment. A list requires that we have a plan if there is data and a backup plan if there is no data. A list requires that we render the same thing for each row, and we don’t know how many rows we have. A list requires that we pass different values for each row, too. Then we have to take the rows and wrap them in a container such as a <ul> or a <table>.

So there is a little more logic here, regardless of whether we use lit-html or any other technique. Let’s explore how the replaceHeroList function renders the rows using lit-html.

function replaceHeroList(heroes?: Hero[]) {
 const heroPlaceholder = document.querySelector('.hero-list');

 // Define the template
 let template: () => TemplateResult;

 if (heroes && heroes.length) {
   // Create the template for every hero row
   template = createList();
 } else {
   // Create the template with a simple "not found" message
   template = () =>
     html`
       <p>heroes not found</p>
     `;
 }

 // Compile the template
 const result = template();

 // Render the template
 render(result, heroPlaceholder);

Notice that when there are heroes, we call the createList function. This function begins by creating an array of TemplateResult. So for every hero in the heroes array, we define a template that represents the <li> containing the HTML that displays that respective hero.

Then we create another template that contains the <ul> and embeds the array of hero templates. It’s pretty cool that we can embed templates like this! Finally, we return it all and let the logic compile the templates and render them.

function createList() {
  // Create an array of the templates for each hero
  const templates: TemplateResult[] = heroes.map(hero => {
    return html`
      <li>
        <div class="card">
          <div class="card-content">
            <div class="content">
              <div class="name">${hero.name}</div>
              <div class="description">${hero.description}</div>
            </div>
          </div>
        </div>
      </li>
    `;
  });

  // Create a template that includes the hero templates
  const ulTemplate: () => TemplateResult = () =>
    html`
      <ul>
        ${templates}
      </ul>
    `;
  return ulTemplate;
}

Summary

When you want to render HTML, lit-html is a fast and light-weight option. Is it better than using templates and the DOM API? You’ll have to decide what is best for you. But the real story here is that you have another great option to consider when determining the right tool for your job.

Prologue

You can also get editor help with your lit-html templates. Notice the image below shows the syntax highlighting for the HTML template!

lit html syntax highlighting

Setup

You can install the lit-html package with npm.

npm install lit-html

Alternately you can load it directly from the unpkg.com CDN

import { html, render } from 'https://unpkg.com/lit-html?module';

You have a choice here. npm is my preference, but feel 100% free to use the CDN if that suits you.

TypeScript and lit-html

You only need to include the library for lit-html and you’re done. But I like to use TypeScript, and I absolutely recommend enabling your tooling to work great with typeScript and lit-html.

Let me be very clear here - you do not need TypeScript. I choose to use it because it helps identify mistakes while I write code. If you don’t want TypeScript, you can opt to use plain JavaScript.

Here are the steps to make TypeScript and lit-html light up together:

  1. Install TypeScript support for lit-html
  2. Configure your tsconfig.json file
  3. Install the VS Code extension for lit-html

Run this command to install the plugin and typescript, as development dependencies to your project.

npm install --save-dev typescript-lit-html-plugin typescript

Edit your tsconfig.json by adding the following to your compilerOptions section.

"compilerOptions": {
  "plugins": [
    {
      "name": "typescript-lit-html-plugin"
    }
  ]
}

Finally, install the VS Code extension for lit-html.

Now you get syntax highlighting for all of your lit-html templates!

#html #javascript #web-development

What is GEEK

Buddha Community

Render HTML with Vanilla JavaScript and lit-html
Lyda White

Lyda White

1628189100

How to Image Uploader with Preview || Html CSS JavaScript

Image Uploader with Preview || Html CSS JavaScript || #html #css #javascript #coding

#html #css #javascript 

Ava Watson

Ava Watson

1595318322

Know Everything About HTML With HTML Experts

HTML stands for a hypertext markup language. For the designs to be displayed in web browser HTML is the markup language. Technologies like Cascading style sheets (CSS) and scripting languages such as JavaScript assist HTML. With the help of HTML websites and the web, designs are created. Html has a wide range of academic applications. HTML has a series of elements. HTML helps to display web content. Its elements tell the web how to display the contents.

The document component of HTML is known as an HTML element. HTML element helps in displaying the web pages. An HTML document is a mixture of text nodes and HTML elements.

Basics of HTML are-

The simple fundamental components oh HTML is

  1. Head- the setup information for the program and web pages is carried in the head
  2. Body- the actual substance that is to be shown on the web page is carried in the body
  3. HTML- information starts and ends with and labels.
  4. Comments- come up in between

Html versions timeline

  1. HTML was created in 1990. Html is a program that is updated regularly. the timeline for the HTML versions is
  2. HTML 2- November, 1995
  3. HTML 3- January, 1997
  4. HTML 4- December, 1997; April, 1998; December, 1999; May, 2000
  5. HTML 5- October, 2014; November, 2016; December, 2017

HTML draft version timelines are

  1. October 1991
  2. June 1992
  3. November 1992
  4. June 1993
  5. November 1993
  6. November 1994
  7. April 1995
  8. January 2008
  9. HTML 5-
    2011, last call
    2012 candidate recommendation
    2014 proposed recommendation and recommendation

HTML helps in creating web pages. In web pages, there are texts, pictures, colouring schemes, tables, and a variety of other things. HTML allows all these on a web page.
There are a lot of attributes in HTML. It may get difficult to memorize these attributes. HTML is a tricky concept. Sometimes it gets difficult to find a single mistake that doesn’t let the web page function properly.

Many minor things are to be kept in mind in HTML. To complete an HTML assignment, it is always advisable to seek help from online experts. These experts are well trained and acknowledged with the subject. They provide quality content within the prescribed deadline. With several positive reviews, the online expert help for HTML assignment is highly recommended.

#html assignment help #html assignment writing help #online html assignment writing help #html assignment help service online #what is html #about html

Deval Desai

Deval Desai

1572250985

Render HTML with Vanilla JavaScript and lit-html

Sometimes you need to render HTML elements on a web page. And like Goldilocks’ search for “just right”, you have to try a few techniques before you find the right one. Using a framework may be too hard. Using pure HTML and the DOM API may be too soft. What you need is something in the middle that is just right. Is lit-html “just right”? Let’s find out.

First, I’ll show how this all works. Then at the end of this article, I’ll explain everything you need to get started with lit-html to try this for yourself.

When you’re done, you can push your HTML app with lit-html to the cloud to see it in all of its glory! I included a link to a free Azure trial, so you can try it yourself.

Resources:

The Sample App

Here is the app I’ll demonstrate in this article. It fetches a list of heroes and renders them when you click the button. It also renders a progress indicator while it is fetching.

Tour of Heroes

What’s the Value of lit-html

When you focus on rendering content, and nothing else, lit-html is a good fit. It works closely with the DOM to render content, and refresh it in an optimal manner. The docs can provide you with more details, but the basic code for lit-html looks like this.

// Credit: As seen in official docs https://lit-html.polymer-project.org/guide/getting-started

// Import lit-html
import { html, render } from 'lit-html';

// Define a template
const myTemplate = name =>
  html`
    <p>Hello ${name}</p>
  `;

// Render the template to the document
render(myTemplate('World'), document.body);

You import lit-html, define a template, then render it to the DOM. That’s it!

Rendering HTML

A progress bar is fairly basic. There is some HTML, and we show it when needed and hide it when it is not required. While we could use a template, or innerHTML, or the DOM API for this, let’s see what this would look like with lit-html.

First, we get a reference to the element in the DOM where the progress bar will appear.

Then we define the template. This code looks and feels like JSX (or TSX). The advantage here is that you can write the HTML. You wrap the HTML in a template string (notice the back-tick character is used and not a single quote). Template strings allow you to span lines and insert variables where needed (we’ll see this soon). The magic that makes this work is the html tag that precedes the template string. The html tag is what tells lit-html that you are about to define a template.

Next, we compile the template and pass those results to lit-html’s render function, which places the results in the DOM. Finally, we hide or show the progress bar as needed.

function showProgress(show = true) {
  const container = document.getElementById('progress-placeholder');

  const template: () => TemplateResult = () => html`
    <progress class="progress is-medium is-info" max="100"></progress>
  `;
  const result = template();
  render(result, container);

  container.style.display = show ? 'block' : 'none';
}

Now you can run this showProgress function any time you want to show the progress bar.

Note that when a template is re-rendered, the only part that is updated is the data that changed. If no data changed, nothing is updated.

Rendering HTML with Dynamic Values

The progress bar does not change each time it is rendered. You will have situations where you want your HTML to change. For example, you may have a message area on your web app that shows a styled message box with a title and a message. The title and message will change every time you show the message area. Now you have dynamic values.

The HTML is defined with a template string, so it is trivial to add a variable into it. Notice the code below adds a title and text into the template, using the ${data.title} and ${data.text} syntax, respectively.

Then the template is compiled and rendered were needed.

When this template is re-rendered, the only part that is updated is the data that changed. In this case, that’s the title and text.

function showMessage(text: string, title = 'Info') {
  const template: (data: any) => TemplateResult = (data: Message) => html`
    <div id="message-box" class="message is-info">
      <h3 class="message-header">${data.title}</h3>
      <p class="message-body">${data.text}</p>
    </div>
  `;

  const el = document.getElementById('message-placeholder');
  const result = template({ title, text });
  render(result, el);

  el.style.visibility = !!text ? 'visible' : 'hidden';
}

Rendering a List

Things get a little more real when we render a list. Let’s think about that for a moment. A list requires that we have a plan if there is data and a backup plan if there is no data. A list requires that we render the same thing for each row, and we don’t know how many rows we have. A list requires that we pass different values for each row, too. Then we have to take the rows and wrap them in a container such as a <ul> or a <table>.

So there is a little more logic here, regardless of whether we use lit-html or any other technique. Let’s explore how the replaceHeroList function renders the rows using lit-html.

function replaceHeroList(heroes?: Hero[]) {
 const heroPlaceholder = document.querySelector('.hero-list');

 // Define the template
 let template: () => TemplateResult;

 if (heroes && heroes.length) {
   // Create the template for every hero row
   template = createList();
 } else {
   // Create the template with a simple "not found" message
   template = () =>
     html`
       <p>heroes not found</p>
     `;
 }

 // Compile the template
 const result = template();

 // Render the template
 render(result, heroPlaceholder);

Notice that when there are heroes, we call the createList function. This function begins by creating an array of TemplateResult. So for every hero in the heroes array, we define a template that represents the <li> containing the HTML that displays that respective hero.

Then we create another template that contains the <ul> and embeds the array of hero templates. It’s pretty cool that we can embed templates like this! Finally, we return it all and let the logic compile the templates and render them.

function createList() {
  // Create an array of the templates for each hero
  const templates: TemplateResult[] = heroes.map(hero => {
    return html`
      <li>
        <div class="card">
          <div class="card-content">
            <div class="content">
              <div class="name">${hero.name}</div>
              <div class="description">${hero.description}</div>
            </div>
          </div>
        </div>
      </li>
    `;
  });

  // Create a template that includes the hero templates
  const ulTemplate: () => TemplateResult = () =>
    html`
      <ul>
        ${templates}
      </ul>
    `;
  return ulTemplate;
}

Summary

When you want to render HTML, lit-html is a fast and light-weight option. Is it better than using templates and the DOM API? You’ll have to decide what is best for you. But the real story here is that you have another great option to consider when determining the right tool for your job.

Prologue

You can also get editor help with your lit-html templates. Notice the image below shows the syntax highlighting for the HTML template!

lit html syntax highlighting

Setup

You can install the lit-html package with npm.

npm install lit-html

Alternately you can load it directly from the unpkg.com CDN

import { html, render } from 'https://unpkg.com/lit-html?module';

You have a choice here. npm is my preference, but feel 100% free to use the CDN if that suits you.

TypeScript and lit-html

You only need to include the library for lit-html and you’re done. But I like to use TypeScript, and I absolutely recommend enabling your tooling to work great with typeScript and lit-html.

Let me be very clear here - you do not need TypeScript. I choose to use it because it helps identify mistakes while I write code. If you don’t want TypeScript, you can opt to use plain JavaScript.

Here are the steps to make TypeScript and lit-html light up together:

  1. Install TypeScript support for lit-html
  2. Configure your tsconfig.json file
  3. Install the VS Code extension for lit-html

Run this command to install the plugin and typescript, as development dependencies to your project.

npm install --save-dev typescript-lit-html-plugin typescript

Edit your tsconfig.json by adding the following to your compilerOptions section.

"compilerOptions": {
  "plugins": [
    {
      "name": "typescript-lit-html-plugin"
    }
  ]
}

Finally, install the VS Code extension for lit-html.

Now you get syntax highlighting for all of your lit-html templates!

#html #javascript #web-development

Alisha Larkin

Alisha Larkin

1617789060

HTML Tutorial For Beginners

The prospect of learning HTML can seem confusing at first: where to begin, what to learn, the best ways to learn — it can be difficult to get started. In this article, we’ll explore the best ways for learning HTML to assist you on your programming journey.

What is HTML?

Hypertext Markup Language (HTML) is the standard markup language for documents meant to be displayed in a web browser. Along with Cascading Style Sheets (CSS) and JavaScript, HTML completes the trio of essential tools used in creating modern web documents.

HTML provides the structure of a webpage, from the header and footer sections to paragraphs of text, videos, and images. CSS allows you to set the visual properties of different HTML elements, like changing colors, setting the order of blocks on the screen, and defining which elements to display. JavaScript automates changes to HTML and CSS, for example, making the font larger in a paragraph when a user clicks a button on the page.

#html #html-css #html-fundamentals #learning-html #html-css-basics #html-templates

ashika eliza

1625652623

HTML - A Complete Guide to Master the Top Programming Language

In this era of technology, anything digital holds a prime significance in our day-to-day life. Hence, developers have submerged themselves to create a major impact using programming languages.According to Statista, HTML/CSS holds the second position (the first being Javascript), in the list of most widely-used programming languages globally (2020).Interested to learn this language? Then head on to this tutorial and get to know all about HTML! Plus we have added numerous examples such that you can learn better! So happy learning!
html for beginners

#html #html-for-beginners #html-tutorials #introduction-to-html #learn-html #tutorials-html