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Utku / Class 19 / Homework Week 3 #244

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Utku / Class 19 / Homework Week 3 #244

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7a154ee
JS2 Week3 Homework Done
allhandsondeck Jan 21, 2019
9584832
corrections with regard to Jim's review
allhandsondeck Jan 23, 2019
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2 changes: 2 additions & 0 deletions .gitignore
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Expand Up @@ -59,3 +59,5 @@ typings/

.netlify
dist/
exercise
live
3 changes: 1 addition & 2 deletions Week3/homework/step2-1.js
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Expand Up @@ -2,8 +2,7 @@

function foo(func) {
// What to do here?
// Replace this comment and the next line with your code
console.log(func);
func();
}

function bar() {
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22 changes: 15 additions & 7 deletions Week3/homework/step2-2.js
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Expand Up @@ -2,19 +2,27 @@

function threeFive(startIndex, stopIndex, threeCallback, fiveCallback) {
const numbers = [];

// Replace this comment and the next line with your code
console.log(startIndex, stopIndex, threeCallback, fiveCallback, numbers);
let i = startIndex;
for (i; i <= stopIndex; i++) {

@remarcmij remarcmij Jan 23, 2019

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You can (and should) declare and initialize the loop index variable i inside the parentheses of the for loop, like this:

for (let i = startIndex; i <= stopIndex; i++) {

Apart from this code being more concise, it also ensures that the i variable is created inside the block scope of the for loop body (because you are, correctly, using let and not var). The way you have done it creates the variable in the local scope of the function where it is not needed.

@allhandsondeck allhandsondeck Jan 23, 2019

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Got it and put it inside of for loop as you show.

if (i % 3 === 0 && i % 5 === 0) {
threeCallback(i);
fiveCallback(i);
} else if (i % 3 === 0) {
threeCallback(i);
} else if (i % 5 === 0) {
fiveCallback(i);
}

@remarcmij remarcmij Jan 23, 2019

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You can simplify this code by using two if statements in a row, rather than chaining them in an if-then-else sequence. Each condition is then tested independently:

if (i % 3 === 0) {
  threeCallback(i);
}
if (i % 5 === 0) {
  fiveCallback(i);
}

@allhandsondeck allhandsondeck Jan 23, 2019

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I was also uncomfortable with these if statement block and then solved more logically as you say.

numbers.push(i);
}
console.log('numbers:', numbers);

@remarcmij remarcmij Jan 23, 2019

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You did not completely follow the assignment here as it asked to create the array first and then loop through the elements (requiring to for loops in a row rather one for loop:

The function should first generate an array containing values from start value to end value (inclusive).

Then the function should take the newly created array and iterate over it, and calling the first callback if the array value is divisible by 3.

@allhandsondeck allhandsondeck Jan 23, 2019

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You're right Sir. I changed sequence and added another for loop for creating array and iterating it.

}

function sayThree(number) {
// Replace this comment and the next line with your code
console.log(number);
console.log(number, 'can divide by 3');

@remarcmij remarcmij Jan 23, 2019

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Just a comment on the English language: 'can divide by 3' -> 'can be divided by 3.'

@allhandsondeck allhandsondeck Jan 23, 2019 •
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Grammar error, corrected.

}

function sayFive(number) {
// Replace this comment and the next line with your code
console.log(number);
console.log(number, 'can divide by 5');
}

threeFive(10, 15, sayThree, sayFive);
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19 changes: 13 additions & 6 deletions Week3/homework/step2-3.js
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Expand Up @@ -5,8 +5,11 @@ function repeatStringNumTimesWithFor(str, num) {
// eslint-disable-next-line
let result = '';

// Replace this comment and the next line with your code
console.log(str, num, result);
if (num > 0) {

@remarcmij remarcmij Jan 23, 2019

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There is no need for this if statement as the test num > 0 is already done by the for loop. The for loop will execute the loop body only while num > 0.

@allhandsondeck allhandsondeck Jan 23, 2019 •
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Absolutely Sir. If statement is deleted.

for (num; num > 0; num--) {
result += str;
}
}

return result;
}
Expand All @@ -18,8 +21,10 @@ function repeatStringNumTimesWithWhile(str, num) {
// eslint-disable-next-line
let result = '';

// Replace this comment and the next line with your code
console.log(str, num, result);
while (num > 0) {
result += str;
num--;
}

return result;
}
Expand All @@ -31,8 +36,10 @@ function repeatStringNumTimesWithDoWhile(str, num) {
// eslint-disable-next-line
let result = '';

// Replace this comment and the next line with your code
console.log(str, num, result);
do {

@remarcmij remarcmij Jan 23, 2019

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Here, you do need to test before entering the loop whether num <= 0. This is because in the case of the do-while loop, the condition is tested at the end of the loop and therefore the loop body is executed at least once. This also makes the do-while loop rather useless in practice, and it can always be rewritten as a regular while loop.

@allhandsondeck allhandsondeck Jan 23, 2019 •
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Got it. I couldn't think that. do-while loop is implemented in if statement.

result += str;
num--;
} while (num > 0);

return result;
}
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4 changes: 3 additions & 1 deletion Week3/homework/step2-4.js
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@@ -1,7 +1,9 @@
'use strict';

function Dog() {
// add your code here
this.name = 'rocky';
this.color = 'red';
this.numLegs = 5;
}

const hound = new Dog();
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7 changes: 5 additions & 2 deletions Week3/homework/step2-5.js
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Expand Up @@ -4,8 +4,11 @@ function multiplyAll(arr) {
// eslint-disable-next-line
let product = 1;

// Replace this comment and the next line with your code
console.log(arr, product);
for (let i = 0; i < arr.length; i++) {
for (let j = 0; j < arr[i].length; j++) {
product = arr[i][j] * product;
}
}

return product;
}
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16 changes: 12 additions & 4 deletions Week3/homework/step2-6.js
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Expand Up @@ -4,13 +4,21 @@ const arr2d = [[1, 2], [3, 4], [5, 6]];
const arr3d = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]];

function printArray2d(arr) {
// Replace this comment and the next line with your code
console.log(arr);
for (let i = 0; i < arr.length; i++) {
for (let j = 0; j < arr[i].length; j++) {
console.log(arr[i][j]);
}
}
}

function printArray3d(arr) {
// Replace this comment and the next line with your code
console.log(arr);
for (let i = 0; i < arr.length; i++) {
for (let j = 0; j < arr[i].length; j++) {
for (let k = 0; k < arr[i][j].length; k++) {
console.log(arr[i][j][k]);
}
}
}
}

printArray2d(arr2d);
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6 changes: 5 additions & 1 deletion Week3/homework/step2-7.js
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Expand Up @@ -20,4 +20,8 @@ f2(y);

console.log(y);

// Add your explanation as a comment here
// Pass by value rule: if you use a variable inside a function and change its value
// it doesn't affect variable's value which is outside of the function.

// Pass by reference rule: if you use a variable's address or reference inside a function
// and change them it affects variable's value which is outside of the function.
4 changes: 2 additions & 2 deletions Week3/homework/step3-bonus.js
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Expand Up @@ -3,8 +3,8 @@
const values = ['a', 'b', 'c', 'd', 'a', 'e', 'f', 'c'];

function makeUnique(arr) {
// Replace this comment and the next line with your code
console.log(arr);
const unique = arr.filter((x, y, z) => z.indexOf(x) === y);
return unique;

@remarcmij remarcmij Jan 23, 2019

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See my comment below with respect to creating the variable unique.

@allhandsondeck allhandsondeck Jan 23, 2019

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Also this one is shorthened.

}

const uniqueValues = makeUnique(values);
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6 changes: 4 additions & 2 deletions Week3/homework/step3.js
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@@ -1,8 +1,10 @@
'use strict';

function createBase(base) {
// Replace this comment and the next line with your code
console.log(base);
return function addSix(num) {
const sum = base + num;
return sum;

@remarcmij remarcmij Jan 23, 2019

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You could just return base + sum directly without creating an intermediate variable sum. However, sometimes it makes sense to create an intermediate variable as you did here if you want to make it absolutely clear how the human reader should interpret the result of the computation.

@allhandsondeck allhandsondeck Jan 23, 2019

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I understand. It is shorthened.

};
}

const addSix = createBase(6);
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