[Javascript] Intro to Recursion - Refactoring to a Pure Function

let input, config, tasks;

input = [‘dist‘];

config = {
  "dist": ["build", "deploy"],
  "build": [‘js‘, ‘css‘, ‘vender‘],
  "js": [‘babel‘, ‘ng-Annotate‘, "uglify"],
  "css": ["sass", "css-min"]
};

tasks = [];

getTasks(input);

function getTasks(input){
  
  input.forEach((task)=>{
    if(config[task]){
      getTasks(config[task]);
    }else{
      tasks.push(task);
    }
  })
};

console.log(tasks);

let input, config, tasks;

input = [‘dist‘];

config = {
  "dist": ["build", "deploy"],
  "build": [‘js‘, ‘css‘, ‘vender‘],
  "js": [‘babel‘, ‘ng-Annotate‘, "uglify"],
  "css": ["sass", "css-min"]
};

tasks = [];

var res = getTasks(input, []);

function getTasks(input, initial){
  
  return input.reduce((prev, next)=>{
    if(config[next]){
      return getTasks(config[next], prev);
    }else{
      return prev.concat(next);
    }
  }, initial);
};

console.log(res);

let input, config;

input = [‘dist‘];

config = {
  "dist": ["build", "deploy"],
  "build": [‘js‘, ‘css‘, ‘vender‘],
  "js": [‘babel‘, ‘ng-Annotate‘, "uglify"],
  "css": ["sass", "css-min"]
};

var res = getTasks(config, input, []);

function getTasks(config, input, initial){
  
  return input.reduce((prev, next)=>{
    if(config[next]){
      return getTasks(config ,config[next], prev);
    }else{
      return prev.concat(next);
    }
  }, initial);
};

console.log(res);