Combine Values of an Array into a String with Join

join.js

// Array.prototype.join();

var name = ['Shane', 'Osbourne'];

// give all the values back as a string and I provide the separator in between
console.log(names.join(' '));  // Shane Osbourne with a space in between
console.log(names.join('-'));  // Shane-Osbourne
console.log(names.join(''));  // ShaneOsbourne
console.log(names.join());  // when not providing any arg at all, you get the values separated with a comma -> Shane,Osbourne

// practical USE CASE:
/* 
    1.Lets say you have a command line program and you want to provide a help screen to users;    
*/
                                  
// store each line of the help text in an array   
var help = [
  'Usage',
  '     foo-app <input>'
]
// check if the user has run the 'help' command by looking at the third argument available tools
if(process.argv[2] === 'help'){
  console.log(help.join('\n')); // takes every item in the help array, puts a new line in between each one and prints the result
}; // prints the values from the help array in the terminal (when users run help in the terminal):
 /*
 Usage
      foo-app <input>
*/

/*
  2. You want to Upper Case the first letter of each word in a String
*/
var name = 'shane osbourne';

var upper = name.split(' ') // [shane, osbourne]
.map(x => x.charAt(0).toUpperCase() + x.slice(1)) // produces another array: [Shane, Osbourne]
.join(' '); //  creates a string: 'Shane Osbourne'

console.log(upper); // 'Shane Osbourne'