[Javascript] Twilio Quest : Javascript Test Lab

25 Mar 2022

Reading time ~2 minutes

Twilio Quest

https://www.twilio.com/quest
TwilioQuest is an educational video game designed to teach a new generation of developers how to change the world with code.
From learning how to use your terminal, to coding in Python, JavaScript, and contributing to Open Source projects, TwilioQuest will help you develop practical engineering skills.

Process.argv

Get input string from the console.
Output is string array.

const argumentValue = process.argv[2];
const treeLifeStatus = Number(argumentValue);

if(treeLifeStatus == 0)
    console.log("alive");
else if(treeLifeStatus == 1)
    console.log("flowering");
else if(treeLifeStatus == 2)
    console.log("shedding");
else
    console.log("other");

String

localCompare
- Get compared result by number(-1, 0, 1) with specific language and options.

const firstValue = process.argv[2];
const secondValue = process.argv[3];

console.log(firstValue.localeCompare(secondValue, 'en', { sensitivity: 'base' }));

Type Casting

string => int, float, double … : Number
int, float, double … => string : String

Number

In javascript, you don’t need to separate Number Type.
int, float, double, log and etc. are all Number.

const numberInput = Number(process.argv[2]);
let output = '';

if (numberInput % 3 == 0) {
  output += 'Java';
}

if (numberInput % 5 == 0) {
  output += 'Script';
}

if (output == "") {
  output = String(numberInput);
}

console.log(output);

Array

map : mapping result from array.

function mutate(freightItems){
    let mutatedItems = [];

    mutatedItems = freightItems.map(item => item.toUpperCase());

    return mutatedItems;
}

const mutated = mutate(['dog', 'ray gun', 'cat']);
console.log('Mutated Items');
console.log(mutated);

reduce : add result from the array. You can also set initial value.

function calculateMass(freightItems){
    let totalMass = 0;

    totalMass = freightItems.reduce((sum, current) => sum + current.length, 0);

    return totalMass;
}

const mass = calculateMass(['dog', 'donkey', 'cat']);
console.log('Total mass of items is ' + mass);

slice : slice array with specific indexes.

function getFirstAmountSorted(inputArray, numberOfItems) {
    inputArray.sort();
    let outputArray = [];
    if(numberOfItems > 0)
        outputArray = inputArray.slice(0, numberOfItems)
    return outputArray;
  }
  
const newArray = getFirstAmountSorted(['cat', 'apple', 'bat'], 2);
console.log(newArray);

filter : filter array with specific function.

function scanAndFilter(freightItems, forbiddenString) {
    let filteredItems = [];
  
    filteredItems = freightItems.filter((item) => {
      return item !== forbiddenString;
    });
  
    return filteredItems;
  }
  
  const filtered = scanAndFilter(
    ["dog", "ray gun", "cat", "zippers", "ray gun"],
    "ray gun"
  );
  console.log("Filtered Items");
  console.log(filtered);

Class

Class can reduce code and make it more reuseable.

Constructor

constructor can initialize members and methods.

Function

When you create function in class, you shouldn’t type function.

class Materializer{
    constructor(targetName){
        this.target = targetName;
        this.activated = false;
    }

    activate(){
        this.activated = true;
    }

    materialize(){
        if(this.activated) return this.target;
        return undefined;
    }
}

Javascript Algorithm Grammer