Lodash and stringDelimiter

For assignment 4.1 I revised to code so that it doesn't end with an empty array element. Martin has commented that the array.filter function is memory intensive, but I haven't been able to figure out a better way to get rid of that empty element. 

For assignment 5.1 I just added the code to make the test cases come out. Getting node.js and lodash to work on a Windows 8 machine was the real challenge for this assignment.
could you chain these two together for a one liner?