JavaScript sample app does not build

🐛 Bug Report

What is the problem?

The default JavaScript project does not build. (TypeScript works just fine with the same steps.)

Reproduction Steps

➜  intro-to-lambda git:(master) ✗ mkdir MyJavaScriptExample
➜  intro-to-lambda git:(master) ✗ cd MyJavaScriptExample
➜  MyJavaScriptExample git:(master) ✗ cdk init --language javascript
Applying project template app for javascript
Executing npm install...
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN my_java_script_example@0.1.0 No repository field.
npm WARN my_java_script_example@0.1.0 No license field.

# Useful commands

 * `npm run test`         check javascript error using the typescript compiler
 * `npm run test:watch`   watch for changes and check javascript error using the typescript compiler
 * `cdk deploy`           deploy this stack to your default AWS account/region
 * `cdk diff`             compare deployed stack with current state
 * `cdk synth`            emits the synthesized CloudFormation template

➜  MyJavaScriptExample git:(master) ✗ npm run build
npm ERR! missing script: build

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/jkodroff/.npm/_logs/2019-09-10T21_44_42_437Z-debug.log

Verbose Log

Environment

• CDK CLI Version: 1.7.0
• Module Version: n/a
• OS: OSX
• Language: JavaScript

Other information

[jogold]

There is no need to build when using JavaScript, you can proceed with cdk commands directly.

The build step in TypeScript compiles to JavaScript.

[shivlaks]

@jkodroff @skinny85 the return code will implicitly be 0 (i.e. echo $? will show that the last command returned a 0) with just the echo, but how about I just make it more explicit anyways:

"echo \"The build step is not required when using Javascript!\" && exit 0"