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

text stringlengths 1 81	start float64 0 10.1k	duration float64 0 24.9
fully intentional, because in JSX, a tag with a capital S gets	1,949.81	5.22
invoked like a function.	1,955.03	1.44
And what does it get invoked with?	1,956.47	1.68
Well, anything you pass it as properties.	1,958.15	2.189
So if you remember properties from HTML, you just	1,960.339	2.041
pass them in line with the key and a value pair.	1,962.38	3.57
In React, you do the exact same thing, and it actually	1,965.95	2.25
gets passed as an object to the component that you described.	1,968.2	4.549
And so now to talk about props.	1,977.8	1.544
Well, props are just past as an object through a component	1,979.344	2.416
and used to compute the return node.	1,981.76	1.5
So basically, the object that we were just referring to in this example,	1,983.26	3.84
we called it a slide.	1,987.1	2.08
In React convention, we always call that props, short for properties,	1,989.18	3.41
like those HTML properties.	1,992.59	4.26
And any change to these props will cause a recomputation of that return node,	1,996.85	4.35
or in React vocab, a re-render.	2,001.2	5.2
And so unlike in HTML, these can be any JavaScript value.	2,006.4	2.97
So if you remember back to HTML, when you declare a property,	2,009.37	3.37
it has to be a string.	2,012.74	1.27
It might be JavaScript, like a JavaScript function,	2,014.01	4.44
but really it's just a string.	2,018.45	2.05
And so you can't pass any complex objects or a date, object, classes,	2,020.5	5.75
instances, and stuff like that.	2,026.25	2.07
But in React, we can pass anything.	2,028.32	1.62
So notice here, slide is an object as declared in the array	2,029.94	5.864
that we have up there.	2,035.804	0.916
And we're just passing the object over there.	2,036.72	2.88
And the way that we pass values in JavaScript	2,039.6	2.22
is we wrap them in single curlies, which means,	2,041.82	3.53
hey, execute this as a JavaScript.	2,045.35	2.55
Does that makes sense?	2,051.594	0.916
So let's actually use a live example of this.	2,056.88	3.5
So there's this website called codesandbox.io,	2,060.38	2.58
which is linked on the website in the Resources tab,	2,062.96	4.44
and this allows us to write React and actually render it live.	2,067.4	4.5
And so can everybody read this?	2,071.9	5.16
So basically, what's on the left over there is code that gets executed	2,081	3.719
and runs live on the right side here.	2,084.719	1.661
So if we started editing this, you see it applied directly on the right side	2,086.38	6.85
there.	2,093.23	2.32
And so you see we have a const called app,	2,095.55	2.862
which doesn't care about any arguments it	2,098.412	1.708
receives and just renders the static HTML here.	2,100.12	6.12
So what if we actually wanted to pass it a prop?	2,106.24	2.38
So say we passed it something like a count and passed it the number 1.	2,108.62	7.43
Again, we use curly braces there to represent this is JavaScript coming,	2,116.05	5.07
and the JavaScript is just the number 1.	2,121.12	3.06
So how might we go ahead and render that in the app?	2,124.18	4.23
Well, first, we need to actually pay attention to the object	2,128.41	4.016
that we receive here.	2,132.426	0.874
And second, we can just do it directly in line.	2,136.86	3.96
And so we use those curly braces to represent,	2,140.82	3.9
hey, here comes some JavaScript.	2,144.72	2.13
And we can just use props.count, and now we'll	2,146.85	5.23
go ahead and grab the prop with the key [? call ?] account.	2,152.08	7.08
And so I mentioned that as props change, React gets re-rendered.	2,159.16	3.57
So how might we do that?	2,162.73	1
Well, we can just wrap this in a set timeout, or a set interval, rather.	2,166.81	4.72
And every 1,000 milliseconds or 1,000 milliseconds,	2,175.53	5.07
let's go ahead and pass it not just one, but the count plus plus,	2,180.6	7.08
where count starts at 0.	2,187.68	5.13
And every time this is invoked, it increments.	2,192.81	6.86
And so down here, we're saying, sudden interval,	2,202.96	2.2
which means run some function every n seconds.	2,205.16	2.42
We set n to equal 1,000 milliseconds, or one second there.	2,207.58	4.57
And every time we want to render this function	2,212.15	2.66
called app with a count of one more than it was last time.	2,214.81	5.091
And so we start at 0, and every second you	2,219.901	1.749
see we pass a new prop count incremented.	2,221.65	5.91
And even though we're not really doing anything actively in the app here,	2,227.56	4.77
we wrote this in a very declarative nature, right?	2,232.33	2.36
We said, for any props that you give me, just render a div with an H2 where	2,234.69	6.43
the H2 is the value of the props.	2,241.12	1.807
See how that's very declarative.	2,242.927	1.333
We don't say, oh, first you have to grab the count,	2,244.26	3.749
then check to see if it is different than the last one,	2,248.009	2.291
and then append this to the DOM.	2,250.3	1.333
We just say, hey, this is what we want.	2,251.633	1.637
And React will give it to us.	2,253.27	3.12
Any questions on React or props thus far?	2,256.39	4.71
Yeah?	2,261.1	0.695
AUDIENCE: [INAUDIBLE]	2,261.795	3.805
JORDAN HAYASHI: Yes, of course.	2,265.6	1.71
So set interval requires two arguments, where the first one is a function.	2,267.31	15
So the question was can you go over the arrow notation here?	2,282.31	5.29
And so set interval expects two arguments.	2,287.6	2.91
One is a function that it will invoke with no arguments,	2,290.51	3.98
and so I'm just declaring an anonymous function here with no arguments.	2,294.49	3.63
So I'm saying, here is a function that takes no arguments,	2,298.12	3.085
and what should I do?	2,301.205	0.875
Well, I should render this.	2,302.08	1.71
I could have also written this as this, and it would have functionally	2,303.79	12.297
been the exact same.	2,316.087	0.833
Does that makes sense?	2,328.614	0.916
Any other questions on React or props?	2,332.27	2.7
Yeah?	2,334.97	0.593
AUDIENCE: So in line 10 [INAUDIBLE]?	2,335.563	2.465
JORDAN HAYASHI: So in line 10, we have braces after the arrow here.	2,344.93	5.72
So that's just saying, interpret all of this as one statement.	2,350.65	5.72

fully intentional, because in JSX, a tag with a capital S gets

1,949.81

5.22

invoked like a function.

1,955.03

1.44

And what does it get invoked with?

1,956.47

1.68

Well, anything you pass it as properties.

1,958.15

2.189

So if you remember properties from HTML, you just

1,960.339

2.041

pass them in line with the key and a value pair.

1,962.38

3.57

In React, you do the exact same thing, and it actually

1,965.95

2.25

gets passed as an object to the component that you described.

1,968.2

4.549

And so now to talk about props.

1,977.8

1.544

Well, props are just past as an object through a component

1,979.344

2.416

and used to compute the return node.

1,981.76

1.5

So basically, the object that we were just referring to in this example,

1,983.26

3.84

we called it a slide.

1,987.1

2.08

In React convention, we always call that props, short for properties,

1,989.18

3.41

like those HTML properties.

1,992.59

4.26

And any change to these props will cause a recomputation of that return node,

1,996.85

4.35

or in React vocab, a re-render.

2,001.2

5.2

And so unlike in HTML, these can be any JavaScript value.

2,006.4

2.97

So if you remember back to HTML, when you declare a property,

2,009.37

3.37

it has to be a string.

2,012.74

1.27

It might be JavaScript, like a JavaScript function,

2,014.01

4.44

but really it's just a string.

2,018.45

2.05

And so you can't pass any complex objects or a date, object, classes,

2,020.5

5.75

instances, and stuff like that.

2,026.25

2.07

But in React, we can pass anything.

2,028.32

1.62

So notice here, slide is an object as declared in the array

2,029.94

5.864

that we have up there.

2,035.804

0.916

And we're just passing the object over there.

2,036.72

2.88

And the way that we pass values in JavaScript

2,039.6

2.22

is we wrap them in single curlies, which means,

2,041.82

3.53

hey, execute this as a JavaScript.

2,045.35

2.55

Does that makes sense?

2,051.594

0.916

So let's actually use a live example of this.

2,056.88

3.5

So there's this website called codesandbox.io,

2,060.38

2.58

which is linked on the website in the Resources tab,

2,062.96

4.44

and this allows us to write React and actually render it live.

2,067.4

4.5

And so can everybody read this?

2,071.9

5.16

So basically, what's on the left over there is code that gets executed

2,081

3.719

and runs live on the right side here.

2,084.719

1.661

So if we started editing this, you see it applied directly on the right side

2,086.38

6.85

there.

2,093.23

2.32

And so you see we have a const called app,

2,095.55

2.862

which doesn't care about any arguments it

2,098.412

1.708

receives and just renders the static HTML here.

2,100.12

6.12

So what if we actually wanted to pass it a prop?

2,106.24

2.38

So say we passed it something like a count and passed it the number 1.

2,108.62

7.43

Again, we use curly braces there to represent this is JavaScript coming,

2,116.05

5.07

and the JavaScript is just the number 1.

2,121.12

3.06

So how might we go ahead and render that in the app?

2,124.18

4.23

Well, first, we need to actually pay attention to the object

2,128.41

4.016

that we receive here.

2,132.426

0.874

And second, we can just do it directly in line.

2,136.86

3.96

And so we use those curly braces to represent,

2,140.82

3.9

hey, here comes some JavaScript.

2,144.72

2.13

And we can just use props.count, and now we'll

2,146.85

5.23

go ahead and grab the prop with the key [? call ?] account.

2,152.08

7.08

And so I mentioned that as props change, React gets re-rendered.

2,159.16

3.57

So how might we do that?

2,162.73

1

Well, we can just wrap this in a set timeout, or a set interval, rather.

2,166.81

4.72

And every 1,000 milliseconds or 1,000 milliseconds,

2,175.53

5.07

let's go ahead and pass it not just one, but the count plus plus,

2,180.6

7.08

where count starts at 0.

2,187.68

5.13

And every time this is invoked, it increments.

2,192.81

6.86

And so down here, we're saying, sudden interval,

2,202.96

2.2

which means run some function every n seconds.

2,205.16

2.42

We set n to equal 1,000 milliseconds, or one second there.

2,207.58

4.57

And every time we want to render this function

2,212.15

2.66

called app with a count of one more than it was last time.

2,214.81

5.091

And so we start at 0, and every second you

2,219.901

1.749

see we pass a new prop count incremented.

2,221.65

5.91

And even though we're not really doing anything actively in the app here,

2,227.56

4.77

we wrote this in a very declarative nature, right?

2,232.33

2.36

We said, for any props that you give me, just render a div with an H2 where

2,234.69

6.43

the H2 is the value of the props.

2,241.12

1.807

See how that's very declarative.

2,242.927

1.333

We don't say, oh, first you have to grab the count,

2,244.26

3.749

then check to see if it is different than the last one,

2,248.009

2.291

and then append this to the DOM.

2,250.3

1.333

We just say, hey, this is what we want.

2,251.633

1.637

And React will give it to us.

2,253.27

3.12

Any questions on React or props thus far?

2,256.39

4.71

Yeah?

2,261.1

0.695

AUDIENCE: [INAUDIBLE]

2,261.795

3.805

JORDAN HAYASHI: Yes, of course.

2,265.6

1.71

So set interval requires two arguments, where the first one is a function.

2,267.31

15

So the question was can you go over the arrow notation here?

2,282.31

5.29

And so set interval expects two arguments.

2,287.6

2.91

One is a function that it will invoke with no arguments,

2,290.51

3.98

and so I'm just declaring an anonymous function here with no arguments.

2,294.49

3.63

So I'm saying, here is a function that takes no arguments,

2,298.12

3.085

and what should I do?

2,301.205

0.875

Well, I should render this.

2,302.08

1.71

I could have also written this as this, and it would have functionally

2,303.79

12.297

been the exact same.

2,316.087

0.833

Does that makes sense?

2,328.614

0.916

Any other questions on React or props?

2,332.27

2.7

Yeah?

2,334.97

0.593

AUDIENCE: So in line 10 [INAUDIBLE]?

2,335.563

2.465

JORDAN HAYASHI: So in line 10, we have braces after the arrow here.

2,344.93

5.72

So that's just saying, interpret all of this as one statement.

2,350.65

5.72