[英]how to put a condition with an addEventListener
hello I have an order form.你好,我有一个订单。 I would like to be able to display an error message if total_qty=0如果 total_qty=0,我希望能够显示错误消息
When the user clicks on validate the order当用户点击验证订单时
<!DOCTYPE html>
<html>
<body>
<button id="btn">validate the order</button>
<span id="total_qte"></span>
<script>
var btn = document.querySelector('#commander);
var total=document.getElementById('total_qty').innerHTML ;
// addEventListener
btn.addEventListener('click', function(){
if (var total== 0){
var p = document.createElement('p');
p.innerText = 'error order;
document.body.appendChild(p); }
});
</script>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<input id="quantity" value="0" type="number">
<button id="btn">validate the order</button>
<div id="errorMessage"></div>
<script>
const btn = document.querySelector('#btn');
// addEventListener
btn.addEventListener('click', function(){
const total = parseFloat(document.getElementById('quantity').value);
console.log("total: ", total);
if ( total === 0){
const p = document.getElementById('errorMessage');
p.innerText = 'error order';
}
else{
const p = document.getElementById('errorMessage');
p.innerText = "";
}
});
</script>
</body>
</html>
<script>
var btn = document.querySelector('#commander');
// addEventListener
btn.addEventListener('click', function(){
var total=document.getElementById('total_qte').innerHTML ;
console.log('TOTAL',total);
if ( total== '0' || parseFloat(total)==0){ // tu avais un espace entre la quote et le zéro..
//alert("Aucun article sélectionner ou votre commande a déjà été envoyée" );
var p = document.createElement('p');
p.innerText = 'Votre commande a déjà été envoyée';
document.body.appendChild(p);
}
});
</script>
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