JavaScript - calculate triangle area

In this article, we would like to show you how to calculate a triangle area using JavaScript.

1. When base and height are given

In this section, we present how to calculate the area of the triangle, when we know its base and height.

  |\
  | \
h |  \ b
  |___\ 
    a

Runnable example:

// ONLINE-RUNNER:browser;

const a = 1; // base
const h = 2; // height

const result = (a * h) / 2;

console.log(`The area of the triangle is ${result}`);

2. When all sides are given

In this section, we use Heron's formula to calculate the area of the triangle when all sides are given.

    /\
   /  \
a /    \ b
 /      \
/________\ 
    c

Runnable example:

// ONLINE-RUNNER:browser;

const a = 3;
const b = 3;
const c = 1;

const s = (a + b + c) / 2; // semi-perimeter

const result = Math.sqrt(s * (s - a) * (s - b) * (s - c));

console.log(`The area of the triangle is ${result}`);

References

1. Triangle - Wikipedia
2. Heron's formula - Wikipedia