JSFiddle - React, Tailwind, and code Playground

HTML

<p id = 'test'>2 + 2 = ?</p><button onClick='oblicz("test", "*",2, 2)'>Odpowiedź</button>

JavaScript

function oblicz(name, operator, a, b) {
       switch(operator) {
           case '+': 
               return alert(a + b); 
               break;
           case '-': 
               return alert(a - b); 
               break;
           case '*': 
               return alert(a * b); 
               break;
           case '/': 
               return alert(a / b); 
               break;
       }
document.getElementById(name).innerHTML = operator;
}