Javascript script to check if number is triangle number.
// © 2017 TheFlyingKeyboard and released under MIT License
// theflyingkeyboard.net
<html>
<body>
Enter a number: <input type="text" id="data">
<button onclick="check()">Convert</button>
<p id="newText"></p>
<script>
function check(){
var data = document.getElementById("data").value;
var n = parseInt(data);
if(isSquare(8 * n + 1)){
document.getElementById("newText").innerHTML = "Number is triangle number";
} else {
document.getElementById("newText").innerHTML = "Number is not triangle number";
}
}
function isSquare(n)
{
for (var i = 0; i < n / 2 + 2; i++)
{
if (i * i == n)
{
return true;
}
}
return false;
}
</script>
</body>
</html>
Javascript Check If Number Is Triangle Number