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NW-6 | Fikret Ellek | JS3| [TECH ED] Array Destructuring | WEEK-3 #311

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NW-6 | Fikret Ellek | JS3| [TECH ED] Array Destructuring | WEEK-3 #311

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0905433
working on arr destruction
fikretellek Feb 25, 2024
13e7a0c
ex 3 done
fikretellek Feb 26, 2024
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2 changes: 1 addition & 1 deletion array-destructuring/exercise-1/exercise.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ const personOne = {
favouriteFood: "Spinach",
};

function introduceYourself(___________________________) {
function introduceYourself({ name, age, favouriteFood }) {
console.log(
`Hello, my name is ${name}. I am ${age} years old and my favourite food is ${favouriteFood}.`
);
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1 change: 1 addition & 0 deletions array-destructuring/exercise-1/readme.md
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Expand Up @@ -18,4 +18,5 @@ The program above will print `Batman is Bruce Wayne`. Notice how we use the `{}`
# Exercise

- What is the syntax to destructure the object `personOne` in exercise.js?
- { name, age, favouriteFood }
- Update the argument of the function `introduceYourself` to use destructuring on the object that gets passed in.
15 changes: 15 additions & 0 deletions array-destructuring/exercise-2/exercise.js
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@@ -1,3 +1,14 @@
function isGryffindor(list) {
list.map(({ firstName, lastName, house }) => {
if (house === "Gryffindor") console.log(firstName, lastName, house);
});
}
function havePet(list) {
list.map(({ firstName, lastName, pet, occupation }) => {
if (pet && occupation === "Teacher") console.log(firstName, lastName, pet);
});
}
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@JackRogers9 JackRogers9 Apr 5, 2024

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Good attempt!

It looks like you are almost there, but be careful when reading requirements, you did not need to log the house in either task, also the first and last name needed to be separated by a space. This code will print HarryPotterGryffindor rather than Harry Potter.

Other improvements:

I would argue however that Array.map() is not the most appropriate method for this task.

Array.map() creates a new instance of an array and returns a value on every iteration, and in this case, you are not assigning the value of this new array to a variable, secondly, you are not returning anything inside the callback function (the function passed into Array.map()).

This means if you assigned the new array to a variable it would just be an array with X number of null values.

In my opinion, there are two improved ways to do this:

First (cleanest):

  list
       .filter( person => person.house === "Gryffindor" )
       .forEach( person => console.log(`${person.firstName} ${person.lastName}`) );

Article on Array.filter() method

Second:

  list.forEach( person => {
     if ( person.house === "Gryffindor" ) 
     {
         console.log(`${person.firstName} ${person.lastName}`)
     }
  } );

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@fikretellek fikretellek May 5, 2024

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Thank you very much Jack, using methods one after another is really simple and effective usage. I didn't think about it before.

I see the difference between map and forEach better now. I always mixed those two.


let hogwarts = [
{
firstName: "Harry",
Expand Down Expand Up @@ -70,3 +81,7 @@ let hogwarts = [
occupation: "Teacher",
},
];

//isGryffindor(hogwarts);

havePet(hogwarts);
14 changes: 13 additions & 1 deletion array-destructuring/exercise-3/exercise.js
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Expand Up @@ -2,7 +2,19 @@ let order = [
{ itemName: "Hot cakes", quantity: 1, unitPrice: 2.29 },
{ itemName: "Apple Pie", quantity: 2, unitPrice: 1.39 },
{ itemName: "Egg McMuffin", quantity: 1, unitPrice: 2.8 },
{ itemName: "Sausage McMuffin", quantity: 1, unitPrice: 3.0 },
{ itemName: "Sausage Muff", quantity: 1, unitPrice: 3.0 },
{ itemName: "Hot Coffee", quantity: 2, unitPrice: 1.0 },
{ itemName: "Hash Brown", quantity: 4, unitPrice: 0.4 },
];

function printBill(list) {
let total = 0;
console.log("QTY", "\t", "ITEM", "\t\t", "TOTAL");
list.map(({ quantity, itemName, unitPrice }) => {
console.log(quantity, "\t", itemName, "\t", unitPrice * quantity);
total += quantity * unitPrice;
});
console.log("Total:", total);
}

printBill(order);
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@JackRogers9 JackRogers9 Apr 5, 2024

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Good job!

Also, an improvement you could make to this solution would be to use Array.reduce() to create a running aggregate instead of defining totalPrice outside of the loop.

Here is a link that explains using reduce to calculate a sum.

https://linuxhint.com/call-reduce-on-an-array-of-objects-to-sum-their-properties/

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@fikretellek fikretellek May 5, 2024

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that's a really useful method. I wish I knew the importance of code review and learn from it long before. Thank you very much for your brilliant and constructive feedback. Sorry for replying after a month. I never knew learning from code review would be this effective. 🙏