Can I make dynamic styles in React Native? - css

Question

Say I have a component with a render like this:
<View style={jewelStyle}></View>
Where jewelStyle =
{
borderRadius: 10,
backgroundColor: '#FFEFCC',
width: 20,
height: 20,
},
How could I make the background colour dynamic and randomly assigned? I've tried
{
borderRadius: 10,
backgroundColor: getRandomColor(),
width: 20,
height: 20,
},
But this makes all instances of View have the same colour, I want each one to be unique.
Any tips?

Answer 1

I usually do something along the lines of:
<View style={this.jewelStyle()} />
...
jewelStyle = function(options) {
return {
borderRadius: 12,
background: randomColor(),
}
}
Every time View is rendered, a new style object will be instantiated with a random color associated with it. Of course, this means that the colors will change every time the component is re-rendered, which is perhaps not what you want. Instead, you could do something like this:
var myColor = randomColor()
<View style={jewelStyle(myColor)} />
...
jewelStyle = function(myColor) {
return {
borderRadius: 10,
background: myColor,
}
}

Answer 2

Yes you can and actually, you should use StyleSheet.create to create your styles.
import React, { Component } from 'react';
import {
StyleSheet,
Text,
View
} from 'react-native';
class Header extends Component {
constructor(props){
super(props);
}
render() {
const { title, style } = this.props;
const { header, text } = defaultStyle;
const combineStyles = StyleSheet.flatten([header, style]);
return (
<View style={ combineStyles }>
<Text style={ text }>
{ title }
</Text>
</View>
);
}
}
const defaultStyle = StyleSheet.create({
header: {
justifyContent: 'center',
alignItems: 'center',
backgroundColor: '#fff',
height: 60,
paddingTop: 15,
shadowColor: '#000',
shadowOffset: { width: 0, height: 3 },
shadowOpacity: 0.4,
elevation: 2,
position: 'relative'
},
text: {
color: '#0d4220',
fontSize: 16
}
});
export default Header;
And then:
<Header title="HOME" style={ {backgroundColor: '#10f1f0'} } />

Answer 3

If you still want to take advantage of StyleSheet.create and also have dynamic styles, try this out:
const Circle = ({initial}) => {
const initial = user.pending ? user.email[0] : user.firstName[0];
const colorStyles = {
backgroundColor: randomColor()
};
return (
<View style={[styles.circle, colorStyles]}>
<Text style={styles.text}>{initial.toUpperCase()}</Text>
</View>
);
};
const styles = StyleSheet.create({
circle: {
height: 40,
width: 40,
borderRadius: 30,
overflow: 'hidden'
},
text: {
fontSize: 12,
lineHeight: 40,
color: '#fff',
textAlign: 'center'
}
});
Notice how the style property of the View is set as an array that combines your stylesheet with your dynamic styles.

Answer 4

The easiest is mine:
<TextInput
style={[
styles.default,
this.props.singleSourceOfTruth ?
{ backgroundColor: 'black' }
: { backgroundColor: 'white' }
]}/>

Answer 5

Had some issue syntactically.
This worked for me
<Text style={[styles.textStyle,{color: 'red'}]}> Hello </Text>
const styles = StyleSheet.create({
textStyle :{
textAlign: 'center',
fontFamily: 'Arial',
fontSize: 16
}
});

Answer 6

You'll want something like this:
var RandomBgApp = React.createClass({
render: function() {
var getRandomColor = function() {
var letters = '0123456789ABCDEF'.split('');
var color = '#';
for (var i = 0; i < 6; i++ ) {
color += letters[Math.floor(Math.random() * 16)];
}
return color;
};
var rows = [
{ name: 'row 1'},
{ name: 'row 2'},
{ name: 'row 3'}
];
var rowNodes = rows.map(function(row) {
return <Text style={{backgroundColor:getRandomColor()}}>{row.name}</Text>
});
return (
<View>
{rowNodes}
</View>
);
}
});
In this example I take the rows array, containing the data for the rows in the component, and map it into an array of Text components. I use inline styles to call the getRandomColor function every time I create a new Text component.
The issue with your code is that you define the style once and therefore getRandomColor only gets called once - when you define the style.

Answer 7

I know this is extremely late, but for anyone still wondering here's an easy solution.
You could just make an array for the styles :
this.state ={
color: "#fff"
}
style={[
styles.jewelstyle, {
backgroundColor: this.state.BGcolor
}
The second will override any original background color as stated in the stylesheet. Then have a function that changes the color:
generateNewColor(){
var randomColor = '#'+Math.floor(Math.random()*16777215).toString(16);
this.setState({BGcolor: randomColor})
}
This will generate a random hex color. Then just call that function whenever and bam, new background color.

Answer 8

Actually, you can write your StyleSheet.create object as a key with function value, it works properly but it has a type issue in TypeScript:
import React from 'react';
import { View, Text, StyleSheet } from 'react-native';
const SomeComponent = ({ bgColor }) => (
<View style={styles.wrapper(bgColor)}>
<Text style={styles.text}>3333</Text>
</View>
);
const styles = StyleSheet.create({
wrapper: color => ({
flex: 1,
backgroundColor: color,
}),
text: {
color: 'red',
},
});

Answer 9

import React, { useContext, useMemo } from 'react';
import { Text, StyleSheet, View } from 'react-native';
import colors from '../utils/colors';
import ThemeContext from './../contexts/ThemeContext';
export default (props) => {
const { theme } = useContext(ThemeContext);
// Constructing styles for current theme
const styles = useMemo(() => createStyles(theme), [theme]);
return (
<View style={styles.container}>
<Text style={styles.label}>{label}</Text>
</View>
);
};
const createStyles = (theme: AppTheme) =>
StyleSheet.create({
container: { width: '100%', position: 'relative', backgroundColor: colors[theme].background },
label: {
fontSize: 13,
fontWeight: 'bold',
},
});
colors.ts
export type AppTheme = 'dark' | 'light';
const light: Colors = {
background: '#FFFFFF',
onBackground: '#333333',
gray: '#999999',
grayLight: '#DDDDDD',
red: 'red',
};
const dark: Colors = {
background: '#333333',
onBackground: '#EEEEEE',
gray: '#999999',
grayLight: '#DDDDDD',
red: 'red',
};
const colors = {
dark,
light,
primary: '#2E9767',
secondary: '#F6D130',
};
export default colors;

Answer 10

Using object spread operator "..." worked for me:
<View style={{...jewelStyle, ...{'backgroundColor': getRandomColor()}}}></View>

Answer 11

Yes, you can make dynamic styles. You can pass values from Components.
First create StyleSheetFactory.js
import { StyleSheet } from "react-native";
export default class StyleSheetFactory {
static getSheet(backColor) {
return StyleSheet.create({
jewelStyle: {
borderRadius: 10,
backgroundColor: backColor,
width: 20,
height: 20,
}
})
}
}
then use it in your component following way
import React from "react";
import { View } from "react-native";
import StyleSheetFactory from './StyleSheetFactory'
class Main extends React.Component {
getRandomColor = () => {
var letters = "0123456789ABCDEF";
var color = "#";
for (var i = 0; i < 6; i++) {
color += letters[Math.floor(Math.random() * 16)];
}
return color;
};
render() {
return (
<View>
<View
style={StyleSheetFactory.getSheet(this.getRandomColor()).jewelStyle}
/>
<View
style={StyleSheetFactory.getSheet(this.getRandomColor()).jewelStyle}
/>
<View
style={StyleSheetFactory.getSheet(this.getRandomColor()).jewelStyle}
/>
</View>
);
}
}

Answer 12

<View
style={[styles.categoryItem,{marginTop: index <= numOfColumns-1 ? 10 : 0 }]}
>

Answer 13

I know there are several answers, but i think the best and most simple is using a state "To change" is the state purpose.
export default class App extends Component {
constructor(props) {
super(props);
this.state = {
style: {
backgroundColor: "white"
}
};
}
onPress = function() {
this.setState({style: {backgroundColor: "red"}});
}
render() {
return (
...
<View style={this.state.style}></View>
...
)
}
}

Answer 14

You can bind state value directly to style object. Here is an example:
class Timer extends Component{
constructor(props){
super(props);
this.state = {timer: 0, color: '#FF0000'};
setInterval(() => {
this.setState({timer: this.state.timer + 1, color: this.state.timer % 2 == 0 ? '#FF0000' : '#0000FF'});
}, 1000);
}
render(){
return (
<View>
<Text>Timer:</Text>
<Text style={{backgroundColor: this.state.color}}>{this.state.timer}</Text>
</View>
);
}
}

Answer 15

If you are using a screen with filters for example, and you want to set the background of the filter regarding if it was selected or not, you can do:
<TouchableOpacity style={this.props.venueFilters.includes('Bar')?styles.filterBtnActive:styles.filterBtn} onPress={()=>this.setFilter('Bar')}>
<Text numberOfLines={1}>
Bar
</Text>
</TouchableOpacity>
On which set filter is:
setVenueFilter(filter){
var filters = this.props.venueFilters;
filters.push(filter);
console.log(filters.includes('Bar'), "Inclui Bar");
this.setState(previousState => {
return { updateFilter: !previousState.updateFilter };
});
this.props.setVenueFilter(filters);
}
PS: the function this.props.setVenueFilter(filters) is a redux action, and this.props.venueFilters is a redux state.

Answer 16

You can do something like this.
In your component:
const getRandomColor = () => {
// you can use your component props here.
}
<View style={[styles.jewelStyle, {backgroundColor: getRandomColor()}]} />
Create your style using stylesheet:
const styles = StyleSheet.create({
jewelStyle: {
backgroundColor: 'red',
},
});

Answer 17

If you are following the functional approach of React-Native, you can use a package called dynamic-styles that tries to solve exactly your problem.
// -- theme.js ------------------------------------------------------
// Initialization of a StyleSheet instance called 'styleSheet'
export const styleSheet = createStyleSheet({
theme: /* optional theme */
});
// -- MyComponent.js -----------------------------------------------
// Create dynamic stylesheet that has access
// to the previously specified theme and parameters
const useStyles = styleSheet.create(({theme, params}) => ({
root: /* Dynamic Styles */,
button: /* Dynamic Styles */,
text: /* Dynamic Styles */,
}));
const MyComponent = (props) => {
// Access dynamic styles using the created 'useStyles()' hook
// and specify the corresponding parameters
const { styles } = useStyles({ color: props.color, fontSize: 10 });
return (
<div className={styles.root}>
{/* */}
</div>
);
}
It basically allows you to create dynamic stylesheets
and link them to functional Components using the React hook pattern.
-> Codesandbox

Answer 18

In case someone needs to apply conditions
selectedMenuUI = function(value) {
if(value==this.state.selectedMenu){
return {
flexDirection: 'row',
alignItems: 'center',
paddingHorizontal: 20,
paddingVertical: 10,
backgroundColor: 'rgba(255,255,255,0.3)',
borderRadius: 5
}
}
return {
flexDirection: 'row',
alignItems: 'center',
paddingHorizontal: 20,
paddingVertical: 10
}
}

Answer 19

Here is what worked for me:
render() {
const { styleValue } = this.props;
const dynamicStyleUpdatedFromProps = {
height: styleValue,
width: styleValue,
borderRadius: styleValue,
}
return (
<View style={{ ...styles.staticStyleCreatedFromStyleSheet, ...dynamicStyleUpdatedFromProps }} />
);
}
For some reason, this was the only way that mine would update properly.

Answer 20

you can use styled-components for react native it will provide you dynamic styling just like emotion or styled-components for web.

Answer 21

For something relatively simple, you can use this approach:
StyleSheet.create({
item: props.selectedId === item.id ? {
backgroundColor: 'red',
}: null
});