JSFiddle - React, Tailwind, and code Playground

HTML

<div class="blueDiv toBeFaddedIn"></div>
<div class="blueDiv toBeFaddedIn"></div>
<div class="blueDiv toBeFaddedIn"></div>
<div class="blueDiv toBeFaddedIn"></div>
<div class="blueDiv toBeFaddedIn"></div>

CSS

.blueDiv {
    background-color: blue;
    height:50px;
    width: 50px;
    display: none;
    
}

JavaScript

function sequentialFadeIn(selectorText, speed, display, callBack) {

    display = display || "block";

    var els = $(selectorText),
        i = 0;

    (function helper() {
        els.eq(i++).fadeIn(speed, helper).css("display", display);
        if (callback && i === els.length) callback(selectorText); // Not really needed any more
    })();
}

sequentialFadeIn(".toBeFaddedIn", "slow", "inline-block", function cleanUp(selectorText1) {
    // not really needed any more
    //  $(selectorText1).removeClass("alreadyFadedIn");
});