JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test"></div>

CSS

.black {
    background-color: black;
    height: 20px;
    width: 20px;
    display: none;
}
html, body {
    height: 100%;
    width: 100%;
}
.test {
    width: 100%;
    height: 100%;
    position: relative;
}

JavaScript

for( var i = 1; i < 136; i++ ) {
    $(".test").append( "<div class='black' id='" + i + "'/></div>" );
}
var els = $(".black");
var $random = shuffleArray( els );

    $random.each( function( ) {
        var max = 4000;
        var min = 1000;
        var duration = Math.floor(Math.random() * ( max - min + 1) + min );
        $(this).delay( duration ).fadeTo( 1000, 1, function( ) {
            $(this).delay( duration ).fadeTo( 1000, 0 );
        });
    });

/**
 * Randomize array element order in-place.
 * Using Fisher-Yates shuffle algorithm.
 */
function shuffleArray(array) {
    for (var i = array.length - 1; i > 0; i--) {
        var j = Math.floor(Math.random() * (i + 1));
        var temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
    return array;
}