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To set inline styles in React:

• Sets the style properties on the element to an object.
• Set specific CSS properties and values ​​to style an element.
• For example,<div style={{backgroundColor: 'salmon', color: 'white'}}>。

const App = () => {
  const stylesObj = {
    backgroundColor: 'lime',
    color: 'white',
  };

  const elementWidth = 150;

  return (
    <div>
      {/* 👇️ 直接设置内联样式 */}
      <div style={{backgroundColor: 'salmon', color: 'white'}}>
        迹忆客
      </div>

      <br />

      {/* 👇️ 使用对象变量设置内联样式 */}
      <div style={stylesObj}>迹忆客</div>

      <br />

      {/* 👇️ 使用三元有条件地设置内联样式 */}
      <div
        style={{
          backgroundColor: 'hi'.length === 2 ? 'violet' : 'mediumblue',
          color: 'hi'.length === 2 ? 'white' : 'mediumpurple',
        }}
      >
        迹忆客
      </div>

      <br />

      {/* 👇️ 设置内联样式将变量插入字符串 */}
      <div
        style={{
          width: `${elementWidth}px`,
          backgroundColor: 'salmon',
          color: 'white',
        }}
      >
        迹忆客
      </div>
    </div>
  );
};

export default App;

Code examples showing various ways to set inline styles on elements in React.js.

The first example sets the style directly on the element.

<div style={{backgroundColor: 'salmon', color: 'white'}}>
  迹忆客
</div>

background-colorNote that multi-word attributes like are camel-cased when set on the style object .

styleThe value of the attribute is enclosed in 2 sets of curly braces.

The first set of curly braces in an inline style mark the start of the expression, and the second set of curly braces is an object containing the style and value.

The second example extracts the style object into a variable.

const App = () => {
  const stylesObj = {
    backgroundColor: 'lime',
    color: 'white',
  };

  return (
    <div>
      {/* 👇️ 使用对象变量设置内联样式 */}
      <div style={stylesObj}>迹忆客</div>
    </div>
  );
};

export default App;

You can use this method when we have multiple elements that share the same style.

We can also conditionally set inline styles in React using the ternary operator.

<div
  style={{
    backgroundColor: 'hi'.length === 2 ? 'violet' : 'mediumblue',
    color: 'hi'.length === 2 ? 'white' : 'mediumpurple',
  }}
>
  迹忆客
</div>

The ternary operator is if/elsevery similar to the statement.

The part before the question mark is evaluated, and if it returns a true value, the operator returns the value before the colon, otherwise it returns the value after the colon.

The ternary operator in the example checks whether the length of the string hi is equal to 2, and if so, backgroundColorreturns the string violet for the attribute, otherwise it returns mediumblue.

We can also use strings to interpolate expressions or variables when setting inline styles.

const App = () => {
  const elementWidth = 150;

  return (
    <div>
      {/* 👇️ 设置内联样式将变量插入字符串 */}
      <div
        style={{
          width: `${elementWidth}px`,
          backgroundColor: 'salmon',
          color: 'white',
        }}
      >
        迹忆客
      </div>
    </div>
  );
};

export default App;

We use template literals to concatenate strings and variables when setting styles.

The div element's widthattribute is set to 150px.

The dollar sign and curly brace syntax allows us to use placeholders that are evaluated.

A common pattern in React is to extract wrapper components with predefined styles that render their child properties.

function BoldText({children}) {
  return <span style={{fontWeight: 'bold'}}>{children}</span>;
}

const App = () => {
  return (
    <div>
      <p>
        Hello <BoldText>World</BoldText>
      </p>
    </div>
  );
};

export default App;

This is a very simple example, but BoldTextthe component sets some styles on an element and renders its children property.

This approach is often used to define wrapper components with commonly reused styles.

Another way to write inline styles in React is to write the styles .cssin a file with the extension .

.bg-salmon {
  background-color: salmon;
}

.text-white {
  color: white;
}

.font-lg {
  font-size: 2rem;
  padding: 10px 10px;
}

Here's how we import and use these classes.

// 👇️ import css file
import './App.css';

const App = () => {
  return (
    <div>
      <p className="bg-salmon text-white font-lg">hello world</p>
    </div>
  );
};

export default App;

When importing global CSS files in React, it is best to import the CSS file into the index.js file.

The index.js file is the entry point of your React application, so it will always be run.

On the other hand, if we import a CSS file into a component, the CSS styles may be removed after the component is unmounted.