Circular Buffer for TypeScript

CircBuffer.ts

export default class CircBuffer<T> {
  data: (T | null)[];

  start: number = 0;
  end: number = 0;
  data_inside: number = 0;

  constructor(public size: number) {
    this.data = new Array(size).fill(null);
  }

  add(value: T) {
    this.data[this.end] = value;

    if (this.data_inside == this.size) {
      // Buffer full, go forward
      this.start = (this.start + 1) % this.size;
      this.end = (this.end + 1) % this.size;
    } else {
      // Buffer not full, move the end
      this.end = (this.end + 1) % this.size;
    }

    if (this.data_inside < this.size) {
      this.data_inside++;
    }
  }

  get(i: number) {
    const index = (this.start + i) % this.size;
    return this.data[index];
  }

  getLast() {
    return this.data[this.end - 1];
  }
}