pre-view/CS50-raw · Datasets at Hugging Face

text stringlengths 1 81	start float64 0 10.1k	duration float64 0 24.9
out the information for each slide.	1,578.93	4.96
And so now let's go ahead and implement that slideshow.	1,583.89	3.652
And so in order to do that, we might have	1,587.542	1.708
something like where we have a slide, which might take an array,	1,589.25	10.52
or it might take an object.	1,599.77	1.26
Let's call it a slide.	1,601.03	2.916
And what will it return?	1,603.946	2.454
Well, it should return a div.	1,606.4	3.597
Maybe inside it we have that H1.	1,609.997	1.333
Then maybe we have that unordered list.	1,615.16	1.64
And then go ahead and close that div.	1,619.359	1.541
So what goes in the H1 here?	1,626.26	2.37
Well, maybe we should have that slide's title.	1,628.63	5.31
And what about generating those bullets?	1,633.94	2.1
Well, like we did in the previous example,	1,636.04	1.75
we might want to do the slide.bullets and map [? overflows ?]	1,637.79	4.01
to create those list items.	1,641.8	2.16
So for each bullet, just go ahead and create a list item	1,643.96	6.196
where you have that bullet.	1,650.156	1.124
And so now we declared exactly what a slide is.	1,657.25	2.48
Well, a slide takes in an object representing	1,659.73	2.79
the slide in the same shape of the object up here.	1,662.52	6.03
And then it just returns the same HTML that we had in the other example.	1,668.55	3.81
It's a div that wraps in H1, where we stick	1,672.36	2.04
in the title, an unordered list that has some list	1,674.4	3.06
items that represent those bullets.	1,677.46	2.409
And now how might we create that slideshow?	1,679.869	1.791
Well, maybe we just do for each slot in the slides,	1,688.45	7.08
maybe we have an outer-wrapping div that maps through the slides.	1,695.53	7.44
And for each slide, we actually just use the slide down there.	1,705.79	5.23
So now we're going to get ahead and use React and generate	1,724.29	5.36
basically the same HTML as we had in the previous one.	1,729.65	3.12
But now say we wanted to change the styling of the title.	1,732.77	3.33
How would we do that?	1,736.1	1.48
Well, that's just right here.	1,737.58	2.33
What about if we wanted to change the structure of how	1,739.91	2.25
we created those bullets?	1,742.16	2.64
In the previous example, if we wanted to wrap the list items in a div,	1,744.8	3.469
it would be many, many lines of code.	1,748.269	1.541
But here, it's just you stick a div here,	1,749.81	2.79
because this is basically an abstract component that says,	1,752.6	3.18
if we wanted to create a slide, here's exactly how we do it.	1,755.78	2.52
Just make sure to pass me a slide of the correct shape.	1,758.3	4.2
And so the React paradigm is to take a very complex problem	1,762.5	3.3
and break it down into small chunks like this	1,765.8	2.28
that each solve a discrete problem in that UI.	1,768.08	4.29
Any questions so far?	1,772.37	1.23
Cool.	1,781.3	0.8
So another great thing is that React is very performant.	1,782.1	3.29
We just write what we want, and React will	1,785.39	1.75
do the hard work of playing with the DOM,	1,787.14	2.67
or changing things so that what we have written	1,789.81	3.33
matches with what we have showing on the page.	1,793.14	3.34
And so the way it does this is through an algorithm called reconciliation.	1,796.48	7.1
And this is the process by which React syncs any changes in app state	1,803.58	3.06
to the DOM.	1,806.64	1.92
So what's great about React is that it actually	1,808.56	2.64
maintains what's called a virtual DOM.	1,811.2	2.67
And so the slow thing about playing with the DOM	1,813.87	3.3
is that anytime you destroy elements or create new elements, that	1,817.17	3.45
takes a relatively long amount of time.	1,820.62	3.33
And so the way that React says, maybe we should do this	1,823.95	3.36
better by rather than changing stuff in the DOM	1,827.31	2.779
every time we want to change something, what if we just stored everything	1,830.089	3.041
in memory?	1,833.13	1.009
And then with any changes, we can just say,	1,834.139	1.791
hey, how does this differ from what's shown on the page?	1,835.93	2.53
And only change what's necessary.	1,838.46	2.03
And so that's what's done in the reconciliation process.	1,840.49	3.03
So first, anytime your data changes, React	1,843.52	3.11
will reconstruct that virtual DOM.	1,846.63	3.12
Then it will diff that DOM against what's actually there in the real DOM.	1,849.75	6.12
And it'll make only the changes that are needed.	1,855.87	2.784
Of course, there is an asterisk that goes along with that,	1,858.654	2.416
but in your mental model, you can just think of it	1,861.07	2.083
as React will just only make the changes as necessary.	1,863.153	5.377
So how the heck do we write React?	1,868.53	3
Well, there's this thing called JSX, which	1,871.53	2.46
is short for JavaScript and XML, which is basically just an XML-like syntax	1,873.99	4.44
extension of JavaScript.	1,878.43	2.349
It's great because it just transpiles directly to JavaScript.	1,880.779	2.541
So as we talked about in an earlier lecture,	1,883.32	2.7
the paradigm now is to rather than just writing JavaScript by hand, using ES5	1,886.02	4.26
directly, we can write in these other languages	1,890.28	2.31
that just transpile back to JavaScript.	1,892.59	2.64
So JSX is an extension to that JavaScript syntax, which will just	1,895.23	3.63
compile back down into JavaScript.	1,898.86	2.7
And so tags defined in JSX, XML looks exactly like HTML with the tags.	1,904.99	6.06
Lowercase tags are treated as HTML or SVG tags,	1,911.05	3.69
whereas things uppercase are treated as our custom components.	1,914.74	4.136
And what the heck is a component?	1,918.876	1.374
Well, a component is just a function, a function that returns a node.	1,920.25	3.387
What's a node?	1,923.637	0.583
It's something that React can render.	1,924.22	2.04
For example, like a div or a span or a string or a number.	1,926.26	3.99
And components will receive an object of properties	1,933.31	3.51
that are passed to this element.	1,936.82	2.25
So going back to the example that we were doing before,	1,939.07	3.15
see how one, we declared a const called slide down here.	1,942.22	5.24
And notice how I uppercased that S. That was	1,947.46	2.35

out the information for each slide.

1,578.93

4.96

And so now let's go ahead and implement that slideshow.

1,583.89

3.652

And so in order to do that, we might have

1,587.542

1.708

something like where we have a slide, which might take an array,

1,589.25

10.52

or it might take an object.

1,599.77

1.26

Let's call it a slide.

1,601.03

2.916

And what will it return?

1,603.946

2.454

Well, it should return a div.

1,606.4

3.597

Maybe inside it we have that H1.

1,609.997

1.333

Then maybe we have that unordered list.

1,615.16

1.64

And then go ahead and close that div.

1,619.359

1.541

So what goes in the H1 here?

1,626.26

2.37

Well, maybe we should have that slide's title.

1,628.63

5.31

And what about generating those bullets?

1,633.94

2.1

Well, like we did in the previous example,

1,636.04

1.75

we might want to do the slide.bullets and map [? overflows ?]

1,637.79

4.01

to create those list items.

1,641.8

2.16

So for each bullet, just go ahead and create a list item

1,643.96

6.196

where you have that bullet.

1,650.156

1.124

And so now we declared exactly what a slide is.

1,657.25

2.48

Well, a slide takes in an object representing

1,659.73

2.79

the slide in the same shape of the object up here.

1,662.52

6.03

And then it just returns the same HTML that we had in the other example.

1,668.55

3.81

It's a div that wraps in H1, where we stick

1,672.36

2.04

in the title, an unordered list that has some list

1,674.4

3.06

items that represent those bullets.

1,677.46

2.409

And now how might we create that slideshow?

1,679.869

1.791

Well, maybe we just do for each slot in the slides,

1,688.45

7.08

maybe we have an outer-wrapping div that maps through the slides.

1,695.53

7.44

And for each slide, we actually just use the slide down there.

1,705.79

5.23

So now we're going to get ahead and use React and generate

1,724.29

5.36

basically the same HTML as we had in the previous one.

1,729.65

3.12

But now say we wanted to change the styling of the title.

1,732.77

3.33

How would we do that?

1,736.1

1.48

Well, that's just right here.

1,737.58

2.33

What about if we wanted to change the structure of how

1,739.91

2.25

we created those bullets?

1,742.16

2.64

In the previous example, if we wanted to wrap the list items in a div,

1,744.8

3.469

it would be many, many lines of code.

1,748.269

1.541

But here, it's just you stick a div here,

1,749.81

2.79

because this is basically an abstract component that says,

1,752.6

3.18

if we wanted to create a slide, here's exactly how we do it.

1,755.78

2.52

Just make sure to pass me a slide of the correct shape.

1,758.3

4.2

And so the React paradigm is to take a very complex problem

1,762.5

3.3

and break it down into small chunks like this

1,765.8

2.28

that each solve a discrete problem in that UI.

1,768.08

4.29

Any questions so far?

1,772.37

1.23

Cool.

1,781.3

0.8

So another great thing is that React is very performant.

1,782.1

3.29

We just write what we want, and React will

1,785.39

1.75

do the hard work of playing with the DOM,

1,787.14

2.67

or changing things so that what we have written

1,789.81

3.33

matches with what we have showing on the page.

1,793.14

3.34

And so the way it does this is through an algorithm called reconciliation.

1,796.48

7.1

And this is the process by which React syncs any changes in app state

1,803.58

3.06

to the DOM.

1,806.64

1.92

So what's great about React is that it actually

1,808.56

2.64

maintains what's called a virtual DOM.

1,811.2

2.67

And so the slow thing about playing with the DOM

1,813.87

3.3

is that anytime you destroy elements or create new elements, that

1,817.17

3.45

takes a relatively long amount of time.

1,820.62

3.33

And so the way that React says, maybe we should do this

1,823.95

3.36

better by rather than changing stuff in the DOM

1,827.31

2.779

every time we want to change something, what if we just stored everything

1,830.089

3.041

in memory?

1,833.13

1.009

And then with any changes, we can just say,

1,834.139

1.791

hey, how does this differ from what's shown on the page?

1,835.93

2.53

And only change what's necessary.

1,838.46

2.03

And so that's what's done in the reconciliation process.

1,840.49

3.03

So first, anytime your data changes, React

1,843.52

3.11

will reconstruct that virtual DOM.

1,846.63

3.12

Then it will diff that DOM against what's actually there in the real DOM.

1,849.75

6.12

And it'll make only the changes that are needed.

1,855.87

2.784

Of course, there is an asterisk that goes along with that,

1,858.654

2.416

but in your mental model, you can just think of it

1,861.07

2.083

as React will just only make the changes as necessary.

1,863.153

5.377

So how the heck do we write React?

1,868.53

3

Well, there's this thing called JSX, which

1,871.53

2.46

is short for JavaScript and XML, which is basically just an XML-like syntax

1,873.99

4.44

extension of JavaScript.

1,878.43

2.349

It's great because it just transpiles directly to JavaScript.

1,880.779

2.541

So as we talked about in an earlier lecture,

1,883.32

2.7

the paradigm now is to rather than just writing JavaScript by hand, using ES5

1,886.02

4.26

directly, we can write in these other languages

1,890.28

2.31

that just transpile back to JavaScript.

1,892.59

2.64

So JSX is an extension to that JavaScript syntax, which will just

1,895.23

3.63

compile back down into JavaScript.

1,898.86

2.7

And so tags defined in JSX, XML looks exactly like HTML with the tags.

1,904.99

6.06

Lowercase tags are treated as HTML or SVG tags,

1,911.05

3.69

whereas things uppercase are treated as our custom components.

1,914.74

4.136

And what the heck is a component?

1,918.876

1.374

Well, a component is just a function, a function that returns a node.

1,920.25

3.387

What's a node?

1,923.637

0.583

It's something that React can render.

1,924.22

2.04

For example, like a div or a span or a string or a number.

1,926.26

3.99

And components will receive an object of properties

1,933.31

3.51

that are passed to this element.

1,936.82

2.25

So going back to the example that we were doing before,

1,939.07

3.15

see how one, we declared a const called slide down here.

1,942.22

5.24

And notice how I uppercased that S. That was

1,947.46

2.35