Text # | Edit on GitHub |
A React component for displaying text.
Text
supports nesting, styling, and touch handling.
In the following example, the nested title and body text will inherit the fontFamily
from
styles.baseText
, but the title provides its own additional styles. The title and body will
stack on top of each other on account of the literal newlines:
When set to true
, indicates that the view is an accessibility element. The default value
for a Text
element is true
.
See the Accessibility guide for more information.
Line Break mode. This can be one of the following values:
head
- The line is displayed so that the end fits in the container and the missing text
at the beginning of the line is indicated by an ellipsis glyph. e.g., "...wxyz"middle
- The line is displayed so that the beginning and end fit in the container and the
missing text in the middle is indicated by an ellipsis glyph. "ab...yz"tail
- The line is displayed so that the beginning fits in the container and the
missing text at the end of the line is indicated by an ellipsis glyph. e.g., "abcd..."clip
- Lines are not drawn past the edge of the text container.The default is tail
.
numberOfLines
must be set in conjunction with this prop.
clip
is working only for iOS
Used to truncate the text with an ellipsis after computing the text layout, including line wrapping, such that the total number of lines does not exceed this number.
This prop is commonly used with lineBreakMode
.
Invoked on mount and layout changes with
{nativeEvent: {layout: {x, y, width, height}}}
This function is called on long press.
e.g., `onLongPress={this.increaseSize}>``
This function is called on press.
e.g., `onPress={() => console.log('1st')}``
Specifies font weight. The values 'normal' and 'bold' are supported for most fonts. Not all fonts have a variant for each of the numeric values, in that case the closest one is chosen.
Specifies text alignment. The value 'justify' is only supported on iOS and
fallbacks to left
on Android.
Used to locate this view in end-to-end tests.
Lets the user select text, to use the native copy and paste functionality.
Specifies whether fonts should scale to respect Text Size accessibility setting on iOS. The
default is true
.
When true
, no visual change is made when text is pressed down. By
default, a gray oval highlights the text on press down.
Description # | Edit on GitHub |
Both iOS and Android allow you to display formatted text by annotating ranges of a string with specific formatting like bold or colored text (NSAttributedString
on iOS, SpannableString
on Android). In practice, this is very tedious. For React Native, we decided to use web paradigm for this where you can nest text to achieve the same effect.
Behind the scenes, React Native converts this to a flat NSAttributedString
or SpannableString
that contains the following information:
On iOS, you can nest views within your Text component. Here's an example:
In order to use this feature, you must give the view a
width
and aheight
.
The <Text>
element is special relative to layout: everything inside is no longer using the flexbox layout but using text layout. This means that elements inside of a <Text>
are no longer rectangles, but wrap when they see the end of the line.
On the web, the usual way to set a font family and size for the entire document is to write:
When the browser is trying to render a text node, it's going to go all the way up to the root element of the tree and find an element with a font-size
attribute. An unexpected property of this system is that any node can have font-size
attribute, including a <div>
. This was designed for convenience, even though not really semantically correct.
In React Native, we are more strict about it: you must wrap all the text nodes inside of a <Text>
component; you cannot have a text node directly under a <View>
.
You also lose the ability to set up a default font for an entire subtree. The recommended way to use consistent fonts and sizes across your application is to create a component MyAppText
that includes them and use this component across your app. You can also use this component to make more specific components like MyAppHeaderText
for other kinds of text.
React Native still has the concept of style inheritance, but limited to text subtrees. In this case, the second part will be both bold and red.
We believe that this more constrained way to style text will yield better apps:
(Developer) React components are designed with strong isolation in mind: You should be able to drop a component anywhere in your application, trusting that as long as the props are the same, it will look and behave the same way. Text properties that could inherit from outside of the props would break this isolation.
(Implementor) The implementation of React Native is also simplified. We do not need to have a fontFamily
field on every single element, and we do not need to potentially traverse the tree up to the root every time we display a text node. The style inheritance is only encoded inside of the native Text component and doesn't leak to other components or the system itself.
IOS # | Edit on GitHub |
ANDROID # | Edit on GitHub |