Beginner Series #5 Triangular Numbers.js

/*
Description:
Triangular number is the amount of points that can fill equilateral triangle.

Example: the number 6 is a triangular number because all sides of a triangle has the same amount of points.

alt text

Hint!
T(n) = n * (n + 1) / 2,
n - is the size of one side.
T(n) - is the triangular number.
Given a number 'T' from interval [1; 2147483646], find if it is triangular number or not.

Appreciate the feedback!
*/
function isTriangular(t) {
    let x = (Math.sqrt(8 * t + 1) - 1) / 2
    return parseInt(x)===x
}