JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="MyInput" placeholder="Name" />
<input type="button" id="MyButton" value="Toggle Placeholer" />

CSS

#MyInput.blue-placeholder::-webkit-input-placeholder {
    color: #0000ff;
}

JavaScript

$("#MyButton").on("click", function () {
    $("#MyInput").toggleClass("blue-placeholder");
});