JSFiddle - React, Tailwind, and code Playground

HTML

<input id="myInput" value="Default Input Value" />

CSS

#myInput { color: #999; }

JavaScript

var myInput = document.getElementById("myInput");
myInput.onfocus = function () {
    if (this.value == "Default Input Value") {
        this.value = "";
        this.style.color = "#000";
    }
}
myInput.onblur = function () {
    if (this.value == "") {
        this.value = "Default Input Value";
        this.style.color = "#999";
    }
}