runLength.js

// Using the JavaScript language, have the function RunLength(str) take the str parameter being passed and return a compressed // version of the string using the Run-length encoding algorithm. This algorithm works by taking the occurrence of each 
// repeating character and outputting that number along with a single character of the repeating sequence. 
// For example: "wwwggopp" would return 3w2g1o2p. The string will not contain any numbers, punctuation, or symbols. 

// Input = "aabbcde"        Output = "2a2b1c1d1e"
// Input = "wwwbbbw"        Output = "3w3b1w"

function RunLength( str ) {
	var output = '';
	while ( str.length > 0 ) {
		var current = new RegExp( str[0] + '+' );
		var length = str.match( current ).toString().split( '' ).length;
		output += length.toString() + str.match( current )[0][0];
		str = str.replace( str.match( current )[0], '' );
	}
	
	return output;
}