A function to shrink an Array of numbers, example: shrinkArray( [ 10, 20, 200, 250 ], 2 ) -> [ 15, 225 ]

shrinkArray.js

function shrinkArray( arr, newlen ) {
	var avg,
		avglenj,
		i = 0,
		j = 0,
		len = arr.length,
		avglen = ~~( len / newlen ),
		newarr = [];

	for ( ; i < newlen; ++i ) {
		avg = 0;
		avglenj = j + avglen;
		while ( j < avglenj && j < len ) {
			avg += arr[ j++ ];
		}
		newarr.push( avg / avglen );
	}
	return newarr;
}