[Startup Engineering] HW2 Quiz: SSJS Interactive Tutorial(Answer)

Which of the following statements is true about our use of npm and chmod before executing ./market-research.js?
– We need to both install necessary libraries and make the file executable before executing it.

After looking at the source of market-research.js, what variable holds the arguments sent to the script when invoked at the command line?
– process.argv

What do the lines like symbols = symbols || SYMBOLS_DEFAULT; do?
-This is a JS idiom for setting default arguments.

Which of the following are standard node modules, included with the default install?
– fs/util

What is the most likely bug in the marketCapFloat function?
– The function currently assumes dollar values in the billions.

What does csv2console do?
– Reads in data from csvfile, computes and formats derived quantities, and prints these out to STDOUT.

What does buildfn do? (Hint: read this and this if you’ve never heard of closures.)
– Creates and returns a function named response2console, which is parametrized with the values of csvfile and headers from the enclosing scope.

What does the marketResearch function do?
– Constructs a Yahoo Finance API call, and invokes code that first writes the results of that API call to disk and then reads/prints/processes said file

What does the if(require.main == module) conditional block do? Check all that apply. (Hint: see here and here (halfway down the page) if you can’t figure it out from context).
-Parse the stock symbols input at the command line, starting with the process.argv variable and producing the symbols variable.
-Triggers two different blocks of code, one that executes when market-research is invoked from the command line and one that executes when invoked as a module via require.

Why do we use console.error in addition to console.log (Hint: see here)?
– console.error prints to STDERR, while console.log prints to STDOUT. This allows us to print both metadata/error messages and actual output at the same time.

스크린샷 2013-07-07 오전 3.35.27

정답은 올리면 안되는거던가?…[모른다는 투로]

 

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