Workshops de javascript

npm install -g learnyounode
learnyounode

 LEARN YOU THE NODE.JS FOR MUCH WIN!
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 HELLO WORLD
 Exercise 1 of 13

Write a program that prints the text "HELLO WORLD" to the console (stdout).

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## HINTS

To make a Node.js program, create a new file with a .js extension and start writing JavaScript! Execute your program by running it with the
node command. e.g.:

    $ node program.js

You can write to the console in the same way as in the browser:

    console.log("text")

When you are done, you must run:

    $ learnyounode verify program.js

to proceed. Your program will be tested, a report will be generated, and the lesson will be marked 'completed' if you are successful.

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 » To print these instructions again, run: learnyounode print
 » To execute your program in a test environment, run: learnyounode run program.js
 » To verify your program, run: learnyounode verify program.js
 » For help run: learnyounode help

console.log('HELLO WORLD');

$ learnyounode run hello.js

$ learnyounode verify program.js

 LEARN YOU THE NODE.JS FOR MUCH WIN!
─────────────────────────────────────
 BABY STEPS
 Exercise 2 of 13

Write a program that accepts one or more numbers as command-line arguments and prints the sum of those numbers to the console (stdout).

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## HINTS

You can access command-line arguments via the global process object. The process object has an argv property which is an array containing the complete command-line. i.e. process.argv.

To get started, write a program that simply contains:

    console.log(process.argv)

Run it with node program.js and some numbers as arguments. e.g:

    $ node program.js 1 2 3

In which case the output would be an array looking something like:

    [ 'node', '/path/to/your/program.js', '1', '2', '3' ]

You'll need to think about how to loop through the number arguments so  you can output just their sum. The first element of the process.argv array is always 'node', and the second element is always the path to your program.js file, so you need to start at the 3rd element (index 2), adding each item to the total until you reach the end of the array.

Also be aware that all elements of process.argv are strings and you may need to coerce them into numbers. You can do this by prefixing the property with + or passing it to Number(). e.g. +process.argv[2] or Number(process.argv[2]).

learnyounode will be supplying arguments to your program when you run learnyounode verify program.js so you don't need to supply them yourself. To test your program without verifying it, you can invoke it with learnyounode run program.js. When you use run, you are invoking the test environment that learnyounode sets up for each exercise.

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 » To print these instructions again, run: learnyounode print
 » To execute your program in a test environment, run: learnyounode run program.js
 » To verify your program, run: learnyounode verify program.js
 » For help run: learnyounode help

var i = process.argv;
i.shift();
i.shift();// supprime les deux premiers arguments ('node', 'programme.js')
console.log(i.reduce(function(a,b){return a + Number(b)},0));

   var result = 0

    for (var i = 2; i < process.argv.length; i++)
      result += Number(process.argv[i])

    console.log(result)