Objects

Objects are very important and powerful. Below we will start with creating simple objects and work towards building objects that are more complex.

Objects let us store data in much more meaningful and helpful ways, with property names. Each Property of an Object can hold any data-type: Booleans, Numbers, Strings, an Array, an Object, or a Function.

Getting Started

1. Fork this repository
2. Clone this repo from your personal GitHub account.
   • Copy the SSH address on the page
   • Run the command: $ git clone [YOUR SSH ADDRESS] to clone this repo onto your computer.
3. Navigate into the exercise folder, e.g. $ cd prep-js-objects.
4. Run the command: $ npm install to get all other files needed to run the tests.
5. Your work will be entered into the file named objects.js
6. Run your tests with the command $ npm test.

• You will need to enter this command each time you want to run the tests.

1. Make all your tests pass :)

Caveat

Below you may see the term key-value pair, this is just another way of referring to an object's property name (key) and its value.

There may be places where a suggested variable name may have been left out, it is up to you as a programmer to name these variables. Make 'em good!

Also, other the instructions may get vague as you progress through this exercise.

Reference

Js-Basics Slides - Objects Section

Exercises

Plain object and adding properties

Declare a variable named plainBox and set its value to be an empty object.

Next, you will add three properties to this object. Each property declaration expression will be on its own line and ending with semicolons (;). This is just one way of adding properties to an object.

• Add a property named color and set it the name of any color.
• Add a property named size and set it to a number value between 0 and 20.
• Add a property named contents and set it to be an empty array.

An object with properties declared line by line

Declare a variable named stockCar and set its value to be an object with its key-value pairs separated by commas (,). This is a way of declaring a new object and also being able to add property names and values at the moment an object is created.

• add a key named model and set its value to the name of an American car manufacturer.
• add a key named year and set it to be a value above 2000 but below 2016.
• add a key named automaticTransmission and give it a Boolean value of your choice.
• add a key named driver and set it to be null.
• add a key named passengers and set it to be an empty array.

Add new property inside a function

Declare a variable named plainPerson. Set its value to be an empty object with no properties.

Next, declare a function named buildPerson and then define three parameters. The first parameter will be named person and the second will be nameString and the third will be age. Within this function you will modify the person object by:

• adding a property called name and set its value to be the second parameter.
• adding a property called age and set its value to be the third parameter.

The function will return the first parameter.

Finally, invoke your new function while passing in the plainPerson object and additional agrument values, then store the return value in a variable named completePerson. Use console.log three times to print the entire object, just the value at name, and just the value at age.

Display values of objects that are inside an array

Declare a new variable named arrayOfObjects and set it to be this array of objects.

Declare a new function named printProcessedOrdersand set one parameter called orders. Within this function you will return a string that prints the order details to the page in the following format.

Example output:

=====
id:  0
purchase date:  Monday Jan 25 2015 2:01 PM
purchase total:  279.38
=====
id:  1
purchase date:  Monday Jan 27 2015 11:31 AM
purchase total:  79.80
=====
id:  2
purchase date:  Monday Feb 1 2015 7:56 AM
purchase total:  15.62
=====
...

Addition with an object

Declare a new variable named sumObj and set it to be a new object with the properties a, b, and result. Properties 'a' and 'b' will be set to a number and result will be 'undefined.'

Declare a new function named objectAddition. Declare the first parameter, which will be an object. Within this function, you will access the values stored a and b of the object being passed in. Add the these values and store the sum to this object's result property. This function will return the object.

Invoke your function and pass in your object, store the result to a variable named sumObjResultand use console.log to inspect your results.

Go ahead and create some more objects and pass them to this function. Have fun with it.

Print sum function and add as new key-value

Declare a new function named printObj and a single parameter which will be the object from the challenge just above. Within this function you are to print to the screen a message of the operation performed. For Example:

// if this object was passed into your function: { a: 10, b:67, result: 77 }
// it should print a message saying
'10 + 67 = 77'

Before returning this object, add a new property to it named output and set it to be the message that was printed out.

Invoke this function and pass in your object. Further test by changing the values of the object being passed in or create more objects and invoke your function multiple times.

Putting stuff in plainBox

Declare a function named putInPlainBox and a single parameter which will be an object. Within this function, write a FOR loop that adds 10 random number values to the array referenced at the contents property of the object being passed in. This function will return the object.

Invoke your function and pass in your object (which should be plainBox), store the result to a variable named plainBoxResult and use console.log to inspect your results.

Detecting transmission

Declare a function named detectingTranmission and a single parameter which will be an object. Within this function you will check to see if the car has an automatic or manual transmission and print the results on screen.

If `automaticTransmission` is true then print a message saying so. Also, provide an appropriate message for when the its false.

Invoke your function and pass in your stockCar object, store the result to a variable named isAutomaticTransmission and use `console.log` to inspect your results.

Who's driving this thing?!

As you may have noticed that the stockCar doesn't have a driver!

Declare a function named addDriver with two parameters. The first parameter will be an object with represents a car, the other will be a person. Within this function, set the driver value of the stockCar to the second parameter being passed into your function.

Invoke your function and pass in your objects, store the result to a variable named stockCarWithDriver, and inspect your results. Consider using plainPerson as your driver.

Final Boss

Call the posse, we ridin'!

The Dev League instructors want to ride your whip!

Declare a variable named passengerList and set it to be ['Jon', 'Jason', 'Tony', 'Joe', 'Jesse', 'Nigel', 'Kelli', 'Marifel', 'Victor']

Declare a variable named passengerAges and set it to be [19, 12, 21, 22, 16, 9, 19, 20, 15]

Declare a function named addPassengers with three parameters. The first will be a car and the second will be an array of names and the third will be an array of ages. The names and ages are in sequence, e.g. "Jon" is "19", "Jason" is "12".

In the end you will return the car but within the function...

You will have to populate the passengers array on the car object with proper objects that represent a person. Currently you have two arrays, one which contains names and another which contains ages.

You should iterate through the names and ages, pass the values to your buildPerson function to build person objects (remember that this function returns a new object). Don't forget that this function actually takes three arguments, how will you handle that? (you should not have to change your function).

Example of a loaded Car:

Display passengers

Delcare a function named displayPassengers and set one parameter which will be a car. This function should print out each passenger's name and age one line at a time.

example output:

'Jon, age 19, is riding dirty!'
'Jason, age 12, is riding dirty!'
'Tony, age 21, is riding dirty!'
'Joe, age 22, is riding dirty!'
'Jesse, age 16, is riding dirty!'
'Nigel, age 9, is riding dirty!'
'Kelli, age 19, is riding dirty!'
'Marifel, age 19, is riding dirty!'
'Victor, age 19, is riding dirty!'