You can compare finishing the course on codeacademy with finishing any school or course; the one hiring you will ask two questions: 1) What is the quality of this course? 2) How can I judge the applicant's performance against the quality of the course?

For 1) you have an issue: Codeacademy is so new, that the quality of the course cannot be determined by the quality of previous "alumni". The one hiring you has to make an educated guess. He can look at the courses and estimate the quality himself.

This makes 2) hard too, since he will not know if finishing this course in say, two weeks, is excellent or subpar.

It will probably convince the one hiring you that you have a basic command of javascript, but you really need to develop something that shows how this command is rated outside the course.

  - Submit patches to open source js projects and get them accepted
  - Answer questions on http://stackoverflow.com/questions/tagged/javascript
  - Build a js library

This will help validate your codeacedemy skills.