Angular 4 2 中的方法重载

typescript
class Shape {
  calculateArea(shape: string): number {
    switch (shape) {
      case 'circle':
        return this.calculateCircleArea(arguments[1]);
      case 'rectangle':
        return this.calculateRectangleArea(arguments[1], arguments[2]);
      case 'triangle':
        return this.calculateTriangleArea(arguments[1], arguments[2]);
      default:
        throw new Error('Invalid shape');
    }
  }
  private calculateCircleArea(radius: number): number {
    return Math.PI * radius * radius;
  }
  private calculateRectangleArea(length: number, width: number): number {
    return length * width;
  }
  private calculateTriangleArea(base: number, height: number): number {
    return (base * height) / 2;
  }
}
const shape = new Shape();
console.log(shape.calculateArea('circle', 5)); // 输出78.54
console.log(shape.calculateArea('rectangle', 4, 6)); // 输出24
console.log(shape.calculateArea('triangle', 3, 4)); // 输出6