JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="inputField">
<button id="addButton">SC</button>

JavaScript

document.getElementById("addButton").addEventListener("click", function() {
    var input = document.getElementById("inputField");
    var currentValue = input.value;
    if(currentValue.length > 0) {
        input.value = currentValue + " SC";
    } else {
        input.value = "SC";
    }
});