JavaScript: Functions - How to activate cancel button
Question
I'm calling a Javascript window.prompt() and prompting the user to submit an integer number one at a time. if user click "cancel" on the prompt() window, the function should terminate the session but I could not find the function to solve this problem.
My question is, how do I terminate the function upon pressing cancel?
This is my program:
function isOdd(n)
{
return n % 2 == 1; // Checking if the number is odd or not
}
// sentinel-controlled loop here
while (true) {
var n = Number(prompt("Enter an integer (click Cancel to terminate)", "0"));
if(n === -1) {
break;
}
if(isOdd(n)) {
alert(n + " is odd.");
}
else {
alert(n + " is even.");
}
}
// trying to find a solution for cancel button
//document.getElementById("Button ID").click()
//function cancel () {
//var cancelButton = document.getElementById( "cancel");
//}
</script>
</head>
<body>
<form action = "#">
<input id = "cancel" type = "button" value = "cancel">
</form>
<h1>Odd/Even Output</h1>
</body>
2 answers
solution1
2 2020-04-07 21:45:57
"If the user clicks the Cancel button, this function returns null."
var promptResult = prompt(...)
if(!promptResult) {
break;
}
// parse and rest of the function
solution2
1 2020-04-07 21:44:20
Window.prompt returns null if the cancel button is clicked. You need to add in a case to handle that.
var result = prompt("Enter an integer (click Cancel to terminate)", "0");
if(result === null) {
return;
}
var n = Number(result);
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