Creating a radial gradient effect using JavaScript

I've been experimenting with setting a radial gradient as the background of a div using JavaScript. My goal is to have the gradient start in the middle with around 0.8 opacity, gradually fading to 0 towards the edges to create a soft fading effect. I've tried a few approaches, but some didn't work at all and others didn't produce the desired result.

One method that partially worked was applying multiple rgba definitions and reducing the opacity by 0.1 at each step:

arrCircleDivs[i].firstChild.style.backgroundImage = 
    '-webkit-radial-gradient(center,rgba('+r+','+g+','+b+',0.8),
    rgba('+r+','+g+','+b+',0.8),rgba('+r+','+g+','+b+',0.8),rgba('+r+','+g+','+b+',0.7),rgba('+r+','+g+','+b+',0.6),rgba('+r+','+g+','+b+',0.5),rgba('+r+','+g+','+b+',0.4),
    rgba('+r+','+g+','+b+',0.3),rgba('+r+','+g+','+b+',0.2),
    rgba('+r+','+g+','+b+',0.1),rgba('+r+','+g+','+b+',0))';

However, these attempts did not work:

arrCircleDivs[i].firstChild.style.backgroundImage = '-webkit-radial-gradient
    (center, circle cover, rgba(30,87,153,0.7) 0%,rgba(30,87,153,0) 100%);

arrCircleDivs[i].firstChild.style.backgroundImage = '-webkit-gradient
    (radial, center center, 0px, center center, 100%, color-stop(0%,rgba(30,87,153,0.7)), 
    color-stop(100%,rgba(30,87,153,0)));

The error message I encountered was:

Uncaught SyntaxError: Unexpected token ILLEGAL

Is there a way to achieve this desired effect using JavaScript?

javascriptcss

Answer №1

An effective method I have discovered is to utilize element.style=backgroundVar and define your backgroundVar with the desired background:...

For example:

let bg = `background:radial-gradient(circle at 0% 0%, 
                rgba(255,0,0,1), rgba(255,0,0,0) 75%), 
            radial-gradient(circle at 0% 100%, 
                rgba(0,0,255,1), rgba(0,0,255,0) 75%), 
            radial-gradient(circle at 100% 0%, 
                rgba(255,255,0,1), rgba(255,255,0,0) 75%),
            radial-gradient(circle at 100% 100%, 
                rgba(0,255,0,1), rgba(0,255,0,0) 75%);`

        document.getElementById("background").style = bg;

Answer №2

To achieve a radial gradient effect, you can utilize CSS styling techniques. It is important to make use of browser extension functions for consistency across different platforms.

When creating a radial gradient, it is necessary to specify at least two color stops.

Sample Radial Gradient:

Radial Gradient Format

background: radial-gradient(shape size at position, start-color, ..., last-color);
By default, the shape is an ellipse, size is farthest-corner, and the position is in the center.

Radial Gradient with Equally Spaced Color Stops (default setting)

Illustration

A demonstration of a radial gradient with evenly spaced color stops:

#grad {
  background: -webkit-radial-gradient(red, green, blue); /* Supported by Safari 5.1 to 6.0 */
  background: -o-radial-gradient(red, green, blue); /* Supported by Opera 11.6 to 12.0 */
  background: -moz-radial-gradient(red, green, blue); /* Supported by Firefox 3.6 to 15 */
  background: radial-gradient(red, green, blue); /* Standard syntax */
}

Answer №3

Is there a need for JavaScript in this scenario?

An alternative solution could involve applying a new class to 'arrCircleDivs[i].firstChild', such as .new-gradient-class.

Subsequently, utilize this class in your CSS to define the gradients desired.

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