Nascent Personality Manifestation


    0.1.3 • Public • Published


    A CSS background property randomizer capable of transitioning between images, colors, and gradients. Written with vanilla JavaScript by yak.


    Distributed under the MIT License.

    Show support by following me on Twitter and GitHub.

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    Release Notes


    • Published to NPM 🥳
    • Added CDN instructions to README


    • Added a gradient to the demo and README



    Include bRando.js

    Include a copy of bRando.js via one of the following methods.


    If you do not want to download bRando.js, include the following code right before the closing </body> tag:

    <script type="text/javascript" src=""></script>


    Otherwise, download the bRando-0.1.3.min.js file or clone this repository, and include the following code right before the closing </body> tag.

    <script type="text/javascript" src="bRando-0.1.3.min.js"></script>

    Create a background randomizer

    Then create an array of backgrounds to be used (they can include images, colors, and/or gradients):

    // Our array of backgrounds to use
    var backgrounds = [
      "url('')", // we can use images
      "#000", // we can use colors
      "linear-gradient(90deg, rgba(2,0,36,1) 0%, rgba(9,9,121,1) 35%, rgba(0,212,255,1) 100%)" // we can use gradients

    See documentation section for more information on background options.

    Next, we create a background randomizer and save it to a variable called backgroundRandomizer:

    // Create a new background randomizer
    var backgroundRandomizer =
      "div", // Selector string of which elements to change backgrounds on
      backgrounds, // Array of backgrounds
      10000, // Time in milliseconds between background changes
      2500, // Duration in milliseconds of transitions
      true // Whether to cycle through the backgrounds randomly or not

    The new randomizer will automatically begin playing.

    Change the background(s)

    We can manually move to the next background:; // Move to the next background

    Remove the background randomizer

    When we are done with it, we can remove the randomizer from the <div> elements:

    backgroundRandomizer.remove(); // Remove background randomizer

    This will revert the background settings on all selected elements to the state they were before we changed them.


    Create a background randomizer

    Background randomizers are created using the method and are attached to select HTML elements by passing a DOM selector string argument.

    // Create a new background randomizer (
        String <selector>, // String selector .class, #id, or element e.g. "div"
        String[] <background_array>, // Array of background properties to use
        Integer <interval_ms>, // Time between background changes e.g. 10000
        Integer <transition_ms>, // Duration of transition animation e.g. 2500
        Boolean <random_order> // Whether to go through backgrounds at random or not e.g. false
    ); returns the created background randomizer object and automatically plays it. If no elements were found using the selector string, the function returns error code 1 instead.

    If the selector string was already used to create a randomizer, the old randomizer will be removed before creating a new one.

    The background_array may contain any combination of CSS background properties including images, colors, and gradients. See For example:

    // mixed background types
    var backgrounds = [
      "url('')", // image url
      "fixed url('') center no-repeat", // image url with other background properties
      "#ff00ff", // magenta background color in hex code
      "linear-gradient(90deg, rgba(2,0,36,1) 0%, rgba(9,9,121,1) 35%, rgba(0,212,255,1) 100%)", // horizontal blue linear gradient
      "rgb(219, 125, 0)", // orange background color in rgb form
      "rgba(131, 92, 59, 1.0)", // brown background color in rgba form
      "#ff0000f0" // red background color in hex code with alpha code

    ⚠️ Warning:

    Creating too many randomizers will consume large amounts of CPU power—particularly while backgrounds are transitioning.

    ⚠️ Warning:

    If multiple randomizers are attached to an html element the background change intervals will be unpredictable.

    For example:

    // Selects all <div> elements with the class of "stuff"
    var r1 ="div.stuff");
    // Selects all <div> elements including the ones
    // already selected for the above background randomizer
    var r2 ="div");

    If for some reason this is done, make sure to remove the randomizers in reverse order:

    r2.remove(); // Remove the second randomizer first
    r1.remove(); // Then remove the first randomizer

    This way the elements will be properly reverted to the state they were in before the randomizers modified them.

    Start the demo background randomizer

    If no arguments are passed to it will create and return a demo randomizer acting on the <html> element:; // Use the demo background randomizer which acts on <html>

    Check it out on the demo page.

    Manually move to the next background; // Manually move the background randomizer, r1, to the next background

    If the randomizer is currently performing a transition animation, the function will return error code 1 indicating it is already going to the next background. If the randomly chosen background is an image which has not yet preloaded, the function with return error code 2. Otherwise, the function will return 0 indicative of a successful background change.

    Manually move all background randomizers to their next background

    bRando.nextAll(); // Manually move all background randomizers to their next background

    Returns 0 if it successfully moved all randomizers to their next background. Otherwise, the function returns the number of randomizers that failed to change.

    Pause a background randomizer

    r1.pause(); // Pause the background randomizer, r1

    Returns 0 if the randomizer is successfully paused. Otherwise, the functions returns 1 to indicate that the randomizer is already paused.

    Pause all background randomizers

    bRando.pauseAll(); // Pause all background randomizers

    Returns 0 if all the randomizers successfully paused. Otherwise, the function returns the number of randomizers which are already paused.

    Play background randomizer; // Play the background randomizer, r1, if it is currently paused

    Returns 0 if the randomizer was successfully played. Otherwise, the function returns 1 if the randomizer is already playing.

    Play all background randomizers

    bRando.playAll(); // Play all background randomizers that are paused

    Returns 0 if all the randomizers successfully played. Otherwise, the function returns the number of randomizers which are already playing.

    Remove a background randomizer

    r1.remove(); // Remove the background randomizer, r1

    This removes the randomizer and reverts the background settings on the selected element(s). Returns 0 for successful removal.

    Remove all background randomizers

    bRando.removeAll(); // Remove all background randomizers

    This removes all randomizers and reverts the background settings on the selected element(s). Returns 0 for successful removal.


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