Array's has lots of helper functions, that is used all the time when developing js applications. It is super helpful to be able to manipulate an array like removing elements or adding elements at specific indexes. Another helpful function of arrays is to know where a specific item is in the array.
Objects can be used for representing data and it can help structure your code. An object can fx represent a user that has a firstname, surname, profile picture and a list of friends. It is constantly used in javascript and essential to learning the language.
If you struggle to do this weeks homework there are a couple of things to do:
- Watch the class recording. If it for some reason is missing. Then watch these: part 1, part 2
- Read up on objects and arrays here
Its warmup time!
Remove the item in names that is equal to nameToRemove
Copy the code below to your homework
const names = [
"Peter",
"Ahmad",
"Yana",
"kristina",
"Rasmus",
"Samuel",
"katrine",
"Tala",
];
const nameToRemove = "Ahmad";
// Write some code here
// Code done
console.log(names); // ['Peter', 'Yana', 'kristina', 'Rasmus', 'Samuel', 'katrine', 'Tala']Write a function where you speficy your speed in km/h and how far you have to go in km. The function has to return the time it will take to arrive at your destination. The time should be formatted like this: 3 hours and 34 minutes.
Hint: For formatting your best friend is Google!
const travelInformation = {
speed: 50,
destinationDistance: 432,
};
const travelTime = notThisFunctionName(travelInformation);
console.log(travelTime); // 8 hours and 38 minutesconst seriesDurations = [
{
title: "Game of thrones",
days: 3,
hours: 1,
minutes: 0,
},
{
title: "Sopranos",
days: 3,
hours: 14,
minutes: 0,
},
{
title: "The Wire",
days: 2,
hours: 12,
minutes: 0,
},
];How much time of my life have i been watching series on tv? Lets find out! Calculate how much time a tv series have taken as a percentage of an average lifespan of 80 years.
Firstly change the seriesDurations array found above to include your favorite series. Find the duration of a series here: http://tiii.me/
Create a function that logs out the following text using the seriesDurations array:
Game of thrones took 0.01% of my life
Sopranos took 0.012% of my life
The Wire took 0.007% of my life
In total that is 0.2% of my life
Here is an example:
const seriesDurations = [
{
title: "Game of thrones",
days: 3,
hours: 1,
minutes: 0,
},
];
function logOutSeriesText() {
// write code here
}
logOutSeriesText(); // logs out the text found aboveSmart-ease is going back to the basics. As always Smart-ease starts by helping people fix their problems. So lets venture out into the real world and see what we find:
You are sitting at a meeting. A person is presenting some interesting thought that you want to write down. You check your bag, but realise that you forgot to bring your notepad. Hmm you check the internet for an online solution. But you need to signup for them all, too bad... Maybe this could be a worthwhile problem so solve. Lets create a simple and easy to use notepad 📝
The first thing we will create is the functionality to save a note:
Create a variable called notes and assign it to an empty array.
Create a function called saveNote. The saveNote has two parameters:
contentparameter is a string.idis a number.
The saveNote function should push an object to the notes array with the keys content and id. Here is an example
const notes = [];
function saveNote(content, id) {
// write some code here
}
saveNote("Pick up groceries", 1);
saveNote("Do laundry", 2);
console.log(notes); // [{content: 'Pick up groceries', id: 1}, {content: 'Do laundry', id: 2}]Now a user can save a note, but what if a user wants to see a specific note, but only remembers the id? Lets create that functionality for him:
Create a function called getNote. The function has one parameter called id. When calling this function with an id it should return the relevant note object that corresponds to the id. If no id is specified or if the id is not a number, log out an error string.
Hint: Use a for loop.
function getNote(id) {
// your code here
}
const firstNote = getNote(1);
console.log(firstNote); // {content: 'Pick up groceries', id: 1}Now a user can both save and get a note. What if the user just wants to read all his notes? Lets also create that functionality:
Create a function logOutNotesFormatted. When calling the function it should log this string out for every note:
"The note with id: 1, has the following note text: "some example note"."
function logOutNotesFormatted() {
// your code here
}
logOutNotesFormatted(); // should log out the text below
// The note with id: 1, has the following note text: Pick up groceries
// The note with id: 2, has the following note text: Do laundrySuddenly you get this great idea for making the note app even better!
Come up with a unique feature you think would make this app better. Write down the idea and see if you can implement it. If not dont worry :) If it is too hard to implement try and ask in the slack channel :)
Try an interactive version 💻 of your code here. Remember to insert your code in the top of the codepen :)
After a long day you come home to relax. The first thing you do is find your phone and start watching some youtube. Then check facebook, and then reading some news. Suddently a hour has passed. What happened to all that time you think to yourself. Maybe we can create some program to help with this problem! What if we could help users manage their smart phone usage?
Its going to work like this: A user can add smartphone activities. Then he can see a status on how his smartphone usage is going.
Lets create the first part of the functionality that is adding activities.
Create a variable called activities that stores all activities of the day. What type of variable would you think would make sense?
Create a function called addActivity. It should have three parameters: date, activity and duration. The date should be a string, the activity a string and the duration a number. To save the activity push an object that contains the date, the activity and the duration to the activities variable.
Now a user can add an activity by writing:
addActivity("23/7/18", "Youtube", 30);
/*
activities should now look like this
[{
date: '23/7/18',
activity: 'Youtube',
duration: 30,
}]
*/Just adding activities wont help the user very much, we need to add some functionality to show the user how his smart phone usage is going.
Create a function called showStatus. This function should use the activities variable and return a string saying the following:
"You have added 3 activities. They amount to 78 min. of usage"
showStatus(activities); // will log out this "You have added 3 activities. They amount to 78 min. of usage"Now what happens if we call showStatus and activities is empty? We need to take that into consideration: If activities is empty log out a string that says: "Add some activities before calling showStatus"
A user asks us if it is possible to set a limit for his smartphone usage. "Off course it is" we promptly reply!
We need to store that limit somewhere, but where and what type should this be?
So how should it work? When showStatus is called and the users usage is above the limit he set. Log out the following string: "You have reached your limit, no more smartphoning for you!"
Try and add some activities and call showStatus
Come up with one feature you think would be helpful for this program.
Optional
- Lets improve the
addActivity, so that we dont need to specify the date, but the function automatically figures out what the date is. Check out this link: https://stackoverflow.com/a/34015511 - Improve the
showStatusfunction by only showing the number of actitivies for that specific day. - Create a function for calculating the activity a user has spent the most time on.
The bonus homework for this week (for those of you want an extra challenge) do the following:
https://www.codewars.com/kata/job-matching-number-1/train/javascript
https://www.codewars.com/kata/job-matching-number-2/train/javascript
https://www.codewars.com/kata/unfinished-loop-bug-fixing-number-1/train/javascript