Find the frequency of each element in an array in typescript

Ts program for Find the frequency of each element in an array. Here more information.

class Occurrence
{
	// Function which is display array elements
	public static display(arr: number[])
	{
	
		console.log(" ",arr);
	}
	// Count occurrence of given array
	public static frequency(arr: number[])
	{
		// Display given array
		Occurrence.display(arr);
		// Create a empty map
		var map = new Map();
		for (var i = 0; i < arr.length; i++)
		{
			if (map.has(arr[i]))
			{
				// When key exists then update value
				map.set(arr[i], map.get(arr[i]) + 1);
			}
			else
			{
				// Add new element
				map.set(arr[i], 1);
			}
		}
		console.log("  Occurrence ");
		//  Display calculated result
		for (const [key,value] of map)
		{
			console.log("  " + key + "  :  " + value);
		}
	}
	public static main(args: string[])
	{
		// Array element
		var arr: number[] = [1, 3, 2, 1, 4, 2, 7, 9, 1, 3, 3, 4, 7];
		Occurrence.frequency(arr);
	}
}
Occurrence.main([]);
/*
 file : code.ts
 tsc --target es6 code.ts
 node code.js
 */

Output

  [ 1, 3, 2, 1, 4, 2, 7, 9, 1, 3, 3, 4, 7 ]
  Occurrence
  1  :  3
  3  :  3
  2  :  2
  4  :  2
  7  :  2
  9  :  1