JSFiddle - React, Tailwind, and code Playground

HTML

<input id="prixOrange" type="number" /><br/>
<button id="calculate">calculer le prix total</button>
<br/>
<p id="result">

</p>

JavaScript

function coutOrange(prixOrange) {
    console.log(prixOrange * 5);
    document.getElementById("result").innerHTML = prixOrange * 5;
}

document.getElementById("calculate").addEventListener('click', function(){
    coutOrange(document.getElementById("prixOrange").value);
});