Why NPM is not available in Docker Conainter

I am very new to docker and playing with it. I am trying to run nodejs app in docker container. I took ubuntu:14.04 as base image and build my own nodeJS baked image. My Dockerfile content looks like below

FROM ubuntu:14.04

MAINTAINER nmrony

#install packages, nodejs and npm
RUN apt-get -y update && \
    apt-get -y install build-essential && \
    curl -sL http://ift.tt/1oa11OK | bash - && \
    apt-get install -y nodejs

#Copy the sources to Container
COPY ./src /src
CMD ["cd /src"]
CMD ["npm install"]

CMD ["nodejs", "/src/server.js"]

I run container using following command

docker run -p 8080:8080 -d --name nodejs_expreriments nmrony/exp-nodejs

It runs fine. But when I try browse http:localhost:8080 it does not run. When I run docker logs nodejs_expreriments, I got the following error

Error: Cannot find module 'express'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (/src/server.js:1:77)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)

I run another container with interactive shell and found that npm is not installed. Can someone help me why NPM is not installed on container? Am I doing something wrong?