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Smarter Layouts with flex-basis and flex

6:42 with Guil Hernandez

Learn how the flex-basis property gives you even more control over the size of flex items, and how the flex shorthand property intelligently sets flexbox values when you don't specify them.

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flex and flex-basis apply to flex items only.
flex-basis specifies the initial main size of a flex item.
You set the initial size you want the flex items to be, then flexbox evenly distributes the free space according that size.
flex is the shorthand for flex-grow, flex-basis and flex-shrink.
Using only one number value for flex sets the flex-grow value of an item.
The second and third values are optional in the flex shorthand.
Setting only one number value for flex automatically sets the flex-basis value to 0.

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To follow along using the latest workspace, 0:00

launch the workspace on this page or you can download the project files. 0:02

In the index.html file the flex container now contains only four items. 0:06

I added content inside each flex item. 0:13

Some items have more content than others, 0:17

as you can see here in the workspace preview. 0:19

Back in flexbox.css when I target the items and 0:21

set their flex-grow value to one. 0:26

The browser tries its best to equally distribute the space inside the container. 0:33

Some flex items are wider than others because of the amount 0:39

of content inside of them but what if your layout requires equal width items? 0:42

Well, this is where the flex-basis property 0:47

can give you even more control over the size of your flex items. 0:50

The flex-basis property works, alongside the flex-grow property, to display equal, 0:54

but flexible, widths for all flex items. 0:59

So, you set the initial size you want the flex items to be, 1:03

then flexbox evenly distributes the free space according to that size. 1:06

flex-basis accepts the same values as the width and height properties. 1:11

So, pixels, ems, percentages, and other units. 1:16

Now, I wanna set the flex items' initial size to 200 pixels. 1:19

So in the item rule I'm going to add 1:24

the flex-basis property and set the value to 200px. 1:27

So in other words the flex items will display 1:33

at an equal size, when they're 200 pixels or wider. 1:37

But if and 1:42

when they're narrower than 200 pixels, the browser will redistribute the space. 1:43

So, let's take a look. 1:48

Great, the space in the flex container is evenly distributed. 1:51

The flex items have flexible widths and 1:56

notice what happens once the flex container starts to get narrow. 1:59

The items begin to break onto multiple lines. 2:04

So, at this point, each flex item is 200 pixels wide. 2:07

Once they're narrower, than the flex-basis value of 200 pixels, 2:12

the browser starts redistributing the space inside the flex container. 2:16

And if I go back and change the items' flex-basis value to 100 pixels, 2:24

The items are now equally sized until they're narrower then 2:31

the flex-basis value of 100 pixels. 2:35

When setting both the flex-grow and flex-basis value of a flex item, 2:43

it's recommended that you use the flex shorthand property, 2:47

instead of the individual properties. 2:51

Let me show you why [SOUND]. 2:54

Flex is the shorthand for flex-grow, flex-basis, and 2:58

a less commonly used flex-shrink property. 3:03

The flex-shrink property does the opposite of flex-grow. 3:06

So instead of growing the item within the available space it shrinks it. 3:11

You can read more about flex-shrink in the teacher's notes. 3:15

The flex shorthand property intelligently sets some of the values for 3:19

you when you don't specify them. 3:23

So for example, I'm going to delete the flex-grow and 3:26

flex-basis properties from the item rule and set the flex value to one. 3:30

Now, using only one number value sets the flex-grow value of the items. 3:34

So here, I'm setting flex-grow to one. 3:42

Now, the second and third values, for flex-shrink and 3:45

flex-basis, are optional in the flex shorthand. 3:49

So, setting one number value still makes the flex items flexible. 3:53

The value one sets the flex-grow to one, and 3:59

it automatically set the flex-basis value to zero. 4:02

Which makes the items proportional within the space the flex container, but the flex 4:07

items do not redistribute the space inside the flex container when it's narrowed. 4:11

As you can see here. 4:17

So, they don't break to new lines. 4:18

Because a flex-basis of zero means that the items can shrink 4:20

all the way to a width of zero pixels. 4:25

Now I still want their initial size to be 200 pixels, so 4:28

I'll go back to the flex property and set the second value in 4:33

the shorthand to 200 pixels this is the flex-basis value [SOUND]. 4:39

So, my layout works exactly like it did earlier, 4:44

before I applied the flex shorthand. 4:48

So, now if I only want to grow the size of an item, 4:51

I can use the flex-grow property on that item so for instance, 4:55

I'll go back to the style sheet and target item two and 4:59

set its flex-grow value to two. 5:05

So item two now gets twice as much space. 5:09

Now I'm not using the flex shorthand here 5:14

because I only want to affect item two's flex-grow factor. 5:18

Using the flex shorthand will reset item two's flex-basis back to zero, 5:22

so, as you can see it doesn't grow at all. 5:28

So, unless you explicitly want to give a flex item a different flex-basis, 5:33

you can simply use flex-grow to expand any of the other items. 5:38

Finally, if you're not setting a flex-basis or flex-shrink value, 5:47

you can still set a flex-grow using the flex shorthand. 5:52

So, in the item rule, I'm going to delete the flex base's value of 200 pixels, 5:57

and then in item two, I'm going to replace the flex-growth 6:03

declaration with the flex shorthand and I'll set the value to two. 6:07

Back in the browser, item two still gets twice as much space as the other flex 6:13

items but remember, the flex shorthand sets the flex-basis value to zero. 6:18

So the flex items do not redistribute the space inside the flex container 6:25

by breaking to a new line. 6:29

Coming up in the next videos, you'll learn how to align flex items on the cross axis, 6:33

and how to achieve perfect horizontal and vertical centering with flex box. 6:37

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