HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.
In CodePen, whatever you write in the HTML editor is what goes within the <body>
tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html>
tag. If you want to add classes there that can affect the whole document, this is the place to do it.
In CodePen, whatever you write in the HTML editor is what goes within the <body>
tags in a basic HTML5 template. If you need things in the <head>
of the document, put that code here.
The resource you are linking to is using the 'http' protocol, which may not work when the browser is using https.
CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.
It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.
To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit-
or -moz-
.
We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).
Any URLs added here will be added as <link>
s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.
You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself.
You can also link to another Pen here (use the .css
URL Extension) and we'll pull the CSS from that Pen and include it. If it's using a matching preprocessor, use the appropriate URL Extension and we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.
JavaScript preprocessors can help make authoring JavaScript easier and more convenient.
Babel includes JSX processing.
Any URL's added here will be added as <script>
s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.
You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.
If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.
You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.
Search for and use JavaScript packages from npm here. By selecting a package, an import
statement will be added to the top of the JavaScript editor for this package.
Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.
All packages are different, so refer to their docs for how they work.
If you're using React / ReactDOM, make sure to turn on Babel for the JSX processing.
If active, Pens will autosave every 30 seconds after being saved once.
If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.
If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.
Visit your global Editor Settings.
<div class="content">
<h1>Simple API wrapper demo</h1>
<p>Read more <a href="https://stanko.github.io/simple-javascript-api-wrapper/" target="_blank">on my blog</a>.</p>
<div>
<button id="req-people">Get People</button>
<button id="req-person">Get Person</button>
<button id="req-404">404 error (with JSON response)</button>
<button id="req-json-error">Invalid JSON response</button>
</div>
<pre id="console"></pre>
<div class="note">
For demo purposes I'm using awesome <a href="https://swapi.co">Star Wars API</a>
</div>
</div>
body {
font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
line-height: 1.2em;
font-size: 16px;
padding: 40px 20px;
color: #24292e;
}
h1 {
font-size: 2em;
margin-bottom: 10px;
}
p {
margin-bottom: 40px;
}
.content {
max-width: 1000px;
position: relative;
margin: 0 auto;
}
pre {
margin-top: 10px;
overflow-x: auto;
font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace;
line-height: 1.3em;
padding: 20px;
border: 1px solid #ddd;
border-radius: 3px;
background: #f6f8fa;
div:not(:last-child) {
border-bottom: 1px solid #ddd;
padding-bottom: 20px;
margin-bottom: 20px;
}
}
button {
margin-right: 5px;
margin-bottom: 5px;
border: 1px solid #ddd;
background: #fff;
font-size: 14px;
border-radius: 50px;
padding: 5px 12px;
transition: all 250ms;
outline: none;
&:hover:not(:disabled) {
color: #2980B9;
border-color: #2980B9;
cursor: pointer;
}
&:disabled {
opacity: 0.5;
}
}
.note {
margin-top: 40px;
color: #ccc;
font-size: 14px;
a {
color: #ccc;
}
}
// ------------------------------------------------------ //
// Simple JavaScript API wrapper
// https://stanko.github.io/simple-javascript-api-wrapper
// ------------------------------------------------------ //
// For demo purposes I'm using this awesome Star Wars API
const API_URL = 'https://swapi.dev/api';
// Custom API error to throw
function ApiError(message, data, status) {
let response = null;
let isObject = false;
// We are trying to parse response
try {
response = JSON.parse(data);
isObject = true;
} catch (e) {
response = data;
}
this.response = response;
this.message = message;
this.status = status;
this.toString = function () {
return `${ this.message }\nResponse:\n${ isObject ? JSON.stringify(this.response, null, 2) : this.response }`;
};
}
// API wrapper function
const fetchResource = (path, userOptions = {}) => {
// Define default options
const defaultOptions = {};
// Define default headers
const defaultHeaders = {};
const options = {
// Merge options
...defaultOptions,
...userOptions,
// Merge headers
headers: {
...defaultHeaders,
...userOptions.headers,
},
};
// Build Url
const url = `${ API_URL }/${ path }`;
// Detect is we are uploading a file
const isFile = options.body instanceof File;
// Stringify JSON data
// If body is not a file
if (options.body && typeof options.body === 'object' && !isFile) {
options.body = JSON.stringify(options.body);
}
// Variable which will be used for storing response
let response = null;
return fetch(url, options)
.then(responseObject => {
// Saving response for later use in lower scopes
response = responseObject;
// HTTP unauthorized
if (response.status === 401) {
// Handle unauthorized requests
// Maybe redirect to login page?
}
// Check for error HTTP error codes
if (response.status < 200 || response.status >= 300) {
// Get response as text
return response.text();
}
// Get response as json
return response.json();
})
// "parsedResponse" will be either text or javascript object depending if
// "response.text()" or "response.json()" got called in the upper scope
.then(parsedResponse => {
// Check for HTTP error codes
if (response.status < 200 || response.status >= 300) {
// Throw error
throw parsedResponse;
}
// Request succeeded
return parsedResponse;
})
.catch(error => {
// Throw custom API error
// If response exists it means HTTP error occured
if (response) {
throw new ApiError(`Request failed with status ${ response.status }.`, error, response.status);
} else {
throw new ApiError(error, null, 'REQUEST_FAILED');
}
});
};
// ------------------------------------------------------ //
// DEMO
// PLEASE NOTE:
// this is a very naive implementation for demo purposes
// ------------------------------------------------------ //
// Define API calls
const getPeople = () => {
return fetchResource('people');
};
const getPerson = (personId) => {
return fetchResource(`people/${ personId }`);
};
const getJsonError = () => {
return fetchResource('not-found');
};
// Get dom nodes
const consoleElement = document.querySelector('#console');
const buttonPeople = document.querySelector('#req-people');
const buttonPerson = document.querySelector('#req-person');
const button404 = document.querySelector('#req-404');
const buttonJsonError = document.querySelector('#req-json-error');
// Create "actions"
function requestPeople() {
// Save button text and set it to loading
const buttonText = this.innerHTML;
this.innerHTML = 'Loading...';
getPeople()
.then(data => {
consoleElement.innerHTML = `<div>${ JSON.stringify(data, null, 2) }</div>${ consoleElement.innerHTML }`;
// Reset button text
this.innerHTML = buttonText;
})
.catch(error => {
consoleElement.innerHTML = `<div>${ error }</div>${ consoleElement.innerHTML }`;
// Reset button text
this.innerHTML = buttonText;
});
}
function requestPerson() {
// Save button text and set it to loading
const buttonText = this.innerHTML;
this.innerHTML = 'Loading...';
getPerson(1)
.then(data => {
consoleElement.innerHTML = `<div>${ JSON.stringify(data, null, 2) }</div>${ consoleElement.innerHTML }`;
// Reset button text
this.innerHTML = buttonText;
})
.catch(error => {
consoleElement.innerHTML = `<div>${ error }</div>${ consoleElement.innerHTML }`;
// Reset button text
this.innerHTML = buttonText;
});
}
function request404() {
// Save button text and set it to loading
const buttonText = this.innerHTML;
this.innerHTML = 'Loading...';
getPerson('not-found')
.then(() => {
// Skipping as it will always fail
})
.catch(error => {
consoleElement.innerHTML = `<div>${ error }</div>${ consoleElement.innerHTML }`;
// Reset button text
this.innerHTML = buttonText;
});
}
function requestJsonError() {
// Save button text and set it to loading
const buttonText = this.innerHTML;
this.innerHTML = 'Loading...';
getJsonError()
.then(() => {
// Skipping as it will always fail
})
.catch(error => {
// Escaping HTML
const errorContent = document.createElement('div');
errorContent.innerText = error;
consoleElement.innerHTML = `<div>${ errorContent.innerHTML }</div>${ consoleElement.innerHTML }`;
// Reset button text
this.innerHTML = buttonText;
});
}
// Bind actions to buttons
buttonPeople.addEventListener('click', requestPeople);
buttonPerson.addEventListener('click', requestPerson);
button404.addEventListener('click', request404);
buttonJsonError.addEventListener('click', requestJsonError);
Also see: Tab Triggers