Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

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.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

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.

+ add another resource

Packages

Add Packages

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.

Behavior

Auto Save

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <div style="width:600px; margin-left:20px;">
  <h4> Interaction with ChatGPT:</h4>
  <p style="font-size: 80%;">ME: "Please generate Javascript/html/css that provides a user slider where, when the slider is on the left, the color of a circle is blue, and when on the right, red."<br><br>
It then generated <u>almost</u> working code.<br><br>
My next request in response: ME: "Thank you.  Unfortunately your code almost worked, but placed the circle <u>over</u> the slider control, preventing dragging the slider.  Can you give me modified code that instead has the colored circle remain in a fixed location at the left-hand edge of the screen?"<br><br>
It's response:<br>"<em>Sure! Here's an updated code that keeps the colored circle at a fixed position on the left-hand edge of the screen, and updates its color based on the position of the slider.<br><br>In this version, the colored circle is positioned using position: absolute and left: 0, which keeps it fixed at the left-hand edge of the screen. The slider is still positioned using position: absolute, but it now has left: 50px to keep it from overlapping with the circle. The JavaScript code has also been simplified, since we no longer need to move the circle in response to the slider. Instead, we just update its background color.</em>"<br><br>
    ME: "There are two issues with the above code:  1) You forgot to actually include the "left: 50px" you refer to.  2) Could you make the code smoothly turn the circle from blue to red, rather than hard-switching at the half-way mark. 3) And can you make the circle change from yellow to red, instead of blue to red."<br><br>
Code then almost worked, but it had a minor color-initialization problem.  I quickly, manually, fixed and changed starting color to green (because yellow, being a color requiring blending of two other colors, got it a little confused).<br>
    The functional result is below.<br><br>
    Note that this is at least a ~10x speedup as compared to (me, not being a Javascript ace) writing from scratch.
  </p>

  <div class="slider-container">
    <input type="range" min="0" max="1" step="0.01" value="0" class="slider" id="mySlider">
    <div class="circle" id="myCircle"></div>
  </div>

</div>


              
            
!

CSS

              
                .slider-container {
  width: 60%;
  height: 50px;
  margin: 25px 0px auto;
  position: relative;
}

.slider {
  position: absolute;
  width: 100%;
  height: 20px;
  top: 15px;
  left: 50px;
}

.circle {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background-color: rgb(0,255,0);
  position: absolute;
  left: 0;
  top: 0;
  transition: background-color 0.2s ease-in-out;
}
              
            
!

JS

              
                const slider = document.getElementById("mySlider");
const circle = document.getElementById("myCircle");

slider.addEventListener("input", () => {
  const value = slider.value;
  const redValue = Math.round(value * 255);
  const greenValue = Math.round((1 - value) * 255);
  const color = `rgb(${redValue}, ${greenValue}, 0)`;
  circle.style.backgroundColor = color;
});
              
            
!
999px

Console