React inline style - style prop expects a mapping from style properties to values, not a string

Question

I am trying to set inline styles in my React application. In this case, for a span:

<span className="myClass" style={{float : 'left', paddingRight : '5px'}} > </span>

React tells me:

Uncaught Invariant Violation: The style prop expects a mapping from style properties to values, not a string. For example, style={{marginRight: spacing + 'em'}} when using JSX. This DOM node was rendered by `SentenceView

I am not quite sure what it means.

PS: I have tried different versions, so I did paddingRight: 5 as well as paddingRight: 5 + 'px' as well as paddingRight : 5px , but I didn't have any success!

Answer 1

Use " style s " prop instead of style

<span className="myClass" style={{float : 'left', paddingRight : '5px'}} > </span>

Here is a great reference from W3Schools which also shows you how to create an object with styling information, and refer to it in the style attribute: reference for how to style React using CSS

Answer 2

There some ways to set style for React Components.

https://facebook.github.io/react/docs/context.html

https://github.com/facebookincubator/create-react-app

1. using style={css_object} or style={{color: this.props.color}}

2. using className="your-class-name"

React REPL

https://jscomplete.com/repl

1 style Object

 // <span style={styles}> const styles = { color: "red", background: "#0f0", fontSize: "32px" }; const BTN = (props) => { return ( <div> My name is <button>{props.name}</button> <hr/> I'm <span style={styles}>{props.age}</span> yeas old! </div> ); }; const infos = { name: "xgqfrms", age: 23 }; ReactDOM.render(<BTN {...infos} />, mountNode); // <span style={{color: styles.color}}> const styles = { color: "red", background: "#0f0", fontSize: "32px" }; const BTN = (props) => { return ( <div> My name is <button>{props.name}</button> <hr/> I'm <span style={{color: styles.color}}>{props.age}</span> yeas old! </div> ); }; const infos = { name: "xgqfrms", age: 23 }; ReactDOM.render(<BTN {...infos} />, mountNode);

2 className & stylesheet.css

 import './styles.css'; /* .classname-color{ color: "red"; background: "#0f0"; } */ const BTN = (props) => { return ( <div> My name is <button>{props.name}</button> <hr/> I'm <span className="classname-color">{props.age}</span> yeas old! </div> ); }; const infos = { name: "xgqfrms", age: 23 }; ReactDOM.render(<BTN {...infos} />, mountNode);

 .classname-color{ color: "red"; background: "#0f0"; }

Answer 3

JSX and HTML are different. See the graphic below from Udemy :

In HTML it is

<div style="background-color: red;"></div>

In JSX you write

<div style={{ backgroundColor: 'red' }}></div>

Conditional inline formatting are different in both.

Answer 4

This is the way how you can define and use inline style with react.

/**
 * Style definitions.
 */
const STYLE = {
    infoColor: {
        color: 'green'
    },
    warningColor: {
        color: 'orange'
    },
    errorColor: {
        color: 'red'
    }
};

/**
 * Component
 */
class Welcome extends React.Component {

    /**
     * Rendering into the DOM.
     */
    render() {
        return (
            <div>
                <h2 style={STYLE.infoColor}>Welcome!</h2>
        )
    }
}

Answer 5

when we use inline styling in react we should always use style={{styleproperties}}

Error:

<input style="margin:0 15px 0 0"/>

Solution:

<input style={{margin:"0 15px 0 0"}}/>

Answer 6

不要将 {{}} 括在双引号或字符串中

Answer 7

Below answer is more informative:
https://stackoverflow.com/a/44733640/984471

Want to share my experience in production project
- I have used the 1st option, copy the style into CSS, and give className in reactjs - this is safe if you have css already with you.
- Not used the 2nd option, because we need to do camel casing like background-color to backgroundColor, where we might go wrong -- so its risky if you have the css already with you.

Answer 8

JSX 和 html 是不同的东西，我们有一些不同的语法来在 jsx 中添加内联 css 我建议阅读整个文档以更好地理解https://www.w3schools.com/react/react_css.asp