Javascript :: Objects II: Examples #js

ObjectsIi:Examples1.js

// takes in and adds arrays or amounts and activities
function lastFridayNight(transactions) {
  let mySum = 0;
  for (let i=0; i < transactions.length; i++) {
    let transaction = transactions[i];
    mySum += transaction.amount;
  }
  return mySum;
}

// refactoring above with Spread functionality:
function lastFridayNight(transactions) {
    let mysum = 0;
    for (let i=0; i < transactions.length; i++) {
        const { amount } = transactions[i];
        
        mysum += amount;
    }
    return mysum;
}

// comparing object keys -- need to test both objects against each other
function compareObjects(obj1, obj2) {
  for (let key in obj1) {
    if (obj1[key] !== obj2[key]) {
      return false;
    }
  }
  for (let key in obj2) {
    if (obj2[key] !== obj1[key]) {
      return false;    
    }
  }
  return true;
}

// translate 1:1 mapping
function leetTranslator(myString) {
  let translation = '';
  for (let i=0; i < myString.length; i++) {
    let currentChar = myString.charAt(i).toLowerCase();
    translation += leetChars[letters.indexOf(currentChar)];
  }
  console.log(translation);
  return translation;
}

// pulling from nested objects, given array:
let animalNoises = [
  { 'dog': {
    'America' : 'Woof! Woof!',
    'Germany' : 'Wau Wau!',
    'England' : 'Bow wow!',
    'Uruguay' : 'Jua jua!',
    'Afrikaans' : 'Blaf!',
    'Korea' : 'Mong mong!',
    'Iceland' : 'Voff voff!',
    'Albania' : 'Ham!',
    'Algeria' : 'Ouaf ouaf!'
    }
  },
  { 'cat': {
    'America' : 'Meow',
    'Germany' : 'Miauw!',
    'England' : 'mew mew',
    'Uruguay' : 'Miau Miau!',
    'Afrikaans' : 'Purr',
    'Korea' : 'Nyaong!',
    'Iceland' : 'Kurnau!',
    'Albania' : 'Miau',
    'Algeria' : 'Miaou!'
    }
  },
  { 'chicken': {
    'America' : 'Cluck cluck',
    'Germany' : 'tock tock tock',
    'England' : 'Cluck Cluck',
    'Uruguay' : 'gut gut gdak',
    'Afrikaans' : 'kukeleku',
    'Korea' : 'ko-ko-ko',
    'Iceland' : 'Chuck-chuck!',
    'Albania' : 'Kotkot',
    'Algeria' : 'Cotcotcodet'
    }
  }
];
function petSounds(animal, country) {
  for (let i = 0; i < animalNoises.length; i++) {
    let currentObj = animalNoises[i];
    let currentSound = currentObj[animal];
    if (currentSound) {
      let animalType = `${animal[0].toUpperCase()}${animal.slice(1)}s`;
      let animalSound = currentSound[country];
      return `${animalType} in ${country} say ${animalSound}`;
    }
  }
}
> [Animals] in [country] say [sound]


// create object counting how many occurrences of a certain letter are in a string
function frequencyAnalysis(string) {
  let charFrequencies = {};
  for (i = 0; i < string.length; i++) {
    let currChar = string[i];
    if (!charFrequencies[currChar]) {
      charFrequencies[currChar] = 1;
    }
    else {
      charFrequencies[currChar]++;
    }
  }
  return charFrequencies;
}


// given an array with nested objects, make new array with day of week attendance per student
let classRoom = [
    {
        "Marnie" : [
                {"Monday" : true},
                {"Tuesday" : true},
                {"Wednesday" : true},
                {"Thursday" : true},
                {"Friday" : true}
            ]
    },
    {
        "Lena" : [
                {"Monday" : false},
                {"Tuesday" : false},
                {"Wednesday" : true},
                {"Thursday" : false},
                {"Friday" : true}
            ]
    },
    {
        "Shoshanna" : [
                {"Monday" : true},
                {"Tuesday" : true},
                {"Wednesday" : false},
                {"Thursday" : true},
                {"Friday" : false}
            ]
    },
    {
        "Jessa" : [
                {"Monday" : false},
                {"Tuesday" : false},
                {"Wednesday" : false},
                {"Thursday" : false},
                {"Friday" : true}
            ]
    }
];

// YOUR CODE BELOW
function attendanceCheck(dayOfWeek) {
  let studentsPresent = [];
  for (let i = 0; i < classRoom.length; i++) {
    let studentObj = classRoom[i];
    let studentName = Object.keys(studentObj)[0]
    let attendanceObjs = studentObj[studentName];
      for (let j = 0; j < attendanceObjs.length; j++) {
        let attendanceObj = attendanceObjs[j];
        let dayName = Object.keys(attendanceObj)[0];
        let presentOnDay = attendanceObj[dayName];
        if (dayName === dayOfWeek && presentOnDay) {
          studentsPresent.push(studentName);
        }
      }
  } return studentsPresent;
}

// Object.entries
// Object.entries: returns an array of arrays, each array within it contains the key/value pair - allowing us to avoid extra work

// so refactor the above to use Object.entries:
function attendanceCheck(dayOfWeek) {
  let studentsPresent = [];
  for (let i = 0; i < classRoom.length; i++) {
    let studentObj = classRoom[i];
    let [studentName, attendanceObjs] = Object.entries(studentObj)[0]
      for (let j = 0; j < attendanceObjs.length; j++) {
        let attendanceObj = attendanceObjs[j];
        let [dayName, presentOnDay] = Object.entries(attendanceObj)[0];
        if (dayName === dayOfWeek && presentOnDay) {
          studentsPresent.push(studentName);
        }
      }
  } return studentsPresent;
}

// writing our own Splice function
function mySplice(anArr, startIdx, deleteCount, ...args) {
  // Store the beginning of the array
  let startElements = [];
  // Store the deleted elements
  let deletedElements = [];
  
  // Take everything from before the startIdx and store it in the startElements array
  for (let i = 0; i < startIdx; i++) {
    startElements.push(anArr.shift());
  }
  
  // Then delete everything by removing an element per deleteCount from the new start of the array
  for (let i = 0; i < deleteCount; i++) {
    deletedElements.push(anArr.shift());
  }
  
  // Insert the added elements into the array
  for (let i = args.length -1; i>=0; i--) {
    let currentArg = args[i];
    anArr.unshift(currentArg);
  }
  
  // reattach the beginning elements onto the array
  for (let i = startElements.length -1; i>=0; i--) {
    let currentStartElement = startElements[i];
    anArr.unshift(currentStartElement);
  }
  // return the deleted elements
  return deletedElements;
}