Example for blog post: Constantly improving the codebase

1.legacy.code.js

var currentYear = 2017
//private function, fetch from DB
function getTodos() {
    return [
        { name: "boogy", checked: true, year: 2014 },
        { name: "alfa", checked: false, year: 2017 },
        { name: "back to the future", checked: false, year: 2021 },
    ]
}

//we need a new functionality, similar with this one
//but instead of OLD entries we need only the future ones
function PublicGetOldTodos() {
    var todosOrig = getTodos()

    //stupid comment like "this filters the todos"
    var todos = new Array();
    var length = todosOrig.length;

    //"this is a loop" comment
    for(var i = 0; i < length; i++)
    {
        if(todosOrig[i].year < currentYear && todosOrig[i].checked == false)
        {
             todos.push(todosOrig[i]);
        }
    }

    //other comments
    if (todos.length == 0) {
        console.log("a dev forgot some code here")
    }
    if (isIE6) {
        //god help us all
    }

    //don't overflow
    if (todos.length > 10){ //10 is a magic number, we hate magic numbers
        return todos.slice(0, 10)
    }

    return todos
}

2.clean.and.refactor.js

//we removed the not used code, added parameters and extract the common functionality
//with the feature we need to implement
function getFilteredTodos(limit = 20, predicate = () => true) {
    var todos = getTodos()

    todos = _.filter(todos, predicate)
    todos = _.slice(todos, 0, limit)

    return todos
}

function PublicGetOldTodos(limit = 10) {
    var condition = (value, index, collection) => {
        return value.year < currentYear && value.checked == false
    }

    return getFilteredTodos(limit, condition)
}

3.new.functionality.js

function PublicGetFutureTodos(limit = 5) {
    var condition = (value, index, collection) => {
        return value.year > currentYear && value.checked == false
    }

    return getFilteredTodos(limit, condition)
}