text stringlengths 1 81 | start float64 0 10.1k | duration float64 0 24.9 |
|---|---|---|
And so now that keeps track of
whether a to do is checked or not. | 5,109.9 | 5.39 |
But the problem is we're not actually
updating our app state every time | 5,115.29 | 3.1 |
a to do is checked or not. | 5,118.39 | 1.82 |
And so we're going to have to
actually handle every single time | 5,120.21 | 4.08 |
an input is clicked. | 5,124.29 | 1.71 |
Every single time it changes, we need
to update our app state accordingly, | 5,126 | 4.35 |
because if you look here, I'm
clicking but nothing is happening. | 5,130.35 | 8.649 |
Why is nothing happening? | 5,138.999 | 1.041 |
Well, we're initializing our
to dos to be checked if false. | 5,140.04 | 4.47 |
We're saying, for each to do, make sure
that checkbox, whether it's checked | 5,144.51 | 4.14 |
or not, is whether that to do-- | 5,148.65 | 2.58 |
its check value is true or false. | 5,151.23 | 1.619 |
But we have no way to
change that from not false, | 5,152.849 | 2.041 |
and so no matter how
many times I click that, | 5,154.89 | 2.76 |
it's not going to change the
value of props.todo.checked. | 5,157.65 | 4.49 |
And so we're going to actually
have to write some logic in order | 5,162.14 | 3.127 |
to handle that. | 5,165.267 | 0.938 |
And so now let's create a new
method, called toggle to do. | 5,170.9 | 4.59 |
We're obviously going to need to
take an argument here, because we | 5,175.49 | 3.33 |
need to know which to do to toggle. | 5,178.82 | 3.69 |
And so what are we going to do here-- | 5,182.51 | 2.92 |
so again, we're going to do
this.setState and we can to dos. | 5,185.43 | 7.04 |
It's this.state.todos.map. | 5,192.47 | 2.12 |
So if you remember back a few lectures
ago, when we talked about filter, map, | 5,207.8 | 5.56 |
and reduce, we talked about how
map applies a function to each | 5,213.36 | 5.67 |
of the values in an
array and will return | 5,219.03 | 3.9 |
a new array with those
values swapped out | 5,222.93 | 3.6 |
with whatever this function returns. | 5,226.53 | 2.4 |
And so how might we use that map
function to handle the toggling of a | 5,228.93 | 5.04 |
to do? | 5,233.97 | 2.64 |
Well, first, which to do
do we actually care about? | 5,236.61 | 4.71 |
We only care about the
to do with an ID that | 5,241.32 | 4.166 |
matches the ID that were passed, right? | 5,245.486 | 1.624 |
So we can immediately
off the bat say, if to do | 5,247.11 | 3.81 |
dot ID is not equal to the ID that
were passed, what should we do? | 5,250.92 | 7.02 |
AUDIENCE: [INAUDIBLE] | 5,257.94 | 1.44 |
JORDAN HAYASHI: Yeah, we
shouldn't do anything, right? | 5,259.38 | 2.25 |
We should just return that to do. | 5,261.63 | 1.65 |
OK, great. | 5,266.02 | 0.5 |
We have one condition, but what happens
with the to do that we want replaced? | 5,266.52 | 4.767 |
We should flip its checked value, right? | 5,275.4 | 3.35 |
And so we're going to want
to return a new object, | 5,278.75 | 4.76 |
and what should those objects' field be? | 5,283.51 | 1.7 |
Well, we can say, ID is to do dot ID. | 5,285.21 | 5.94 |
We can do text is to do dot text. | 5,294.79 | 4.25 |
And what do we want the
checked value to be? | 5,299.04 | 2.11 |
AUDIENCE: [INAUDIBLE] | 5,304.15 | 1.055 |
JORDAN HAYASHI: Yeah, the
opposite of what it was before. | 5,305.205 | 2.375 |
And now it looks like we should
have something that works. | 5,313.4 | 2.93 |
The problem is it doesn't. | 5,319.217 | 1.083 |
It still doesn't change anything
when we click this value. | 5,323.68 | 4.45 |
Anybody have any ideas why not? | 5,328.13 | 2.97 |
It looks like our toggle
to do function should work. | 5,331.1 | 3.9 |
We're setting state,
we're updating the to dos, | 5,335 | 2.829 |
we're mapping over this
with this function, | 5,337.829 | 1.791 |
where if the to do's ID doesn't
match, we don't change it. | 5,339.62 | 2.62 |
But if it does, we flip
the to check value. | 5,342.24 | 2.85 |
But when we click over here,
nothing actually happens. | 5,345.09 | 3.47 |
Why might that be? | 5,348.56 | 1.238 |
Yeah? | 5,349.798 | 0.5 |
AUDIENCE: [INAUDIBLE] | 5,350.298 | 10.187 |
JORDAN HAYASHI: Yeah. | 5,360.485 | 0.875 |
Exactly. | 5,361.36 | 0.5 |
We defined this function, but we're
not actually calling it anywhere. | 5,361.86 | 3.34 |
And so just like we have this
onDelete that passes a new onDelete | 5,365.2 | 3.36 |
function to every single
to do, we should also | 5,368.56 | 2.37 |
have this thing called
onCheck or onToggle that | 5,370.93 | 5.91 |
passes the unique function
to each to do that we | 5,376.84 | 2.82 |
should invoke when we toggle it. | 5,379.66 | 1.56 |
And so let's have an arrow
function here so we don't | 5,381.22 | 3.6 |
have to worry about the this binding. | 5,384.82 | 2.73 |
And when on toggle's invoked, we should
do this.toggleTodo with the todos.id. | 5,387.55 | 5.43 |
And so now since we're
passing a new prop here, | 5,397.822 | 1.958 |
we should probably invoke
that prop at some point. | 5,399.78 | 2.083 |
And so where are we going to do it? | 5,404.202 | 1.458 |
Well, we can do it in the input. | 5,405.66 | 2.77 |
We can do something like
onChange = props.onToggle. | 5,408.43 | 5.99 |
And how do I know that this
on change attribute exists? | 5,418.44 | 2.44 |
Well, you can read the
docs and it'll be there. | 5,420.88 | 2.06 |
Or you can wait till
the next lecture, when | 5,422.94 | 1.95 |
we talk about event handling in React. | 5,424.89 | 2.19 |
And so now we can create a to do. | 5,427.08 | 3.24 |
And when we click it,
look at that-- it works. | 5,430.32 | 3.22 |
Cool. | 5,436.635 | 0.5 |
So now we're tracking every single
to do, whether it's checked or not. | 5,437.135 | 4.28 |
But that wasn't really the goal, right? | 5,441.415 | 1.625 |
The underlying goal was to keep
track of how many to dos there were, | 5,443.04 | 2.833 |
and how many unchecked to dos there are. | 5,445.873 | 2.277 |
And so how might we do that? | 5,448.15 | 1.88 |
Well, first let's create some divs. | 5,453.79 | 1.816 |
This div says to do count. | 5,460.7 | 4.41 |
And then we're going to have
some JavaScript in line there, | 5,467.72 | 3.57 |
and then maybe a div for
unchecked to do count. | 5,471.29 | 6.99 |
And again, some JavaScript. | 5,478.28 | 3.535 |
Cool. | 5,481.815 | 0.5 |
And so what is a quick and easy way
to calculate how many to dos we have? | 5,482.315 | 5.265 |
We're tracking all of
our to dos in memory. | 5,492.39 | 2.14 |
What are we using to track them? | 5,494.53 | 2.23 |
Yeah? | 5,496.76 | 0.5 |
AUDIENCE: [INAUDIBLE] | 5,497.26 | 1.715 |
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