Styled-components--V4 injectGlobal的弃用

注：在styled-component V4版本中injectGlobal API除去，取而代之的是createGlobalStyle样式组件。

也就是说以前的 injectGlobal 全局样式在V4版本代替为使用 createGlobalStyle 渲染组件的方式来使用全局样式。

---

官方文档说明（地址：https://www.styled-components.com）：

A helper method to write global CSS. It does not return a component, but adds the styles to the stylesheet directly.

ARGUMENTS	DESCRIPTION
1. TaggedTemplateLiteral	A tagged template literal with your global styles inside.

import { injectGlobal } from 'styled-components' 

injectGlobal` 
@font-face { 
    font-family: "Operator Mono"; 
    src: url("../fonts/Operator-Mono.ttf"); 
} 
body { 
    margin: 0; 
} 
` 

We do not encourage the use of this. Try to use it once per app at most, if you must, contained in a single file. This is an escape hatch. Only use it for the rare @font-face definition or body styling.

---

createGlobalStyle 官方说明：

A helper function to generate a special StyledComponent that handles global styles. Normally, styled components are automatically scoped to a local CSS class and therefore isolated from other components. In the case of createGlobalStyle, this limitation is removed and things like CSS resets or base stylesheets can be applied.

ARGUMENTS	DESCRIPTION
1. TaggedTemplateLiteral	A tagged template literal with your CSS and interpolations.

Returns a StyledComponent that does not accept children. Place it at the top of your React tree and the global styles will be injected when the component is "rendered".

import { createGlobalStyle } from 'styled-components'

const GlobalStyle = createGlobalStyle`
  body {
    color: ${props => (props.whiteColor ? 'white' : 'black')};
  }
`

// later in your app


   {/* example of other top-level stuff */}
  

Since the GlobalStyle component is a StyledComponent, that means it also has access to theming from the  component if provided.

import { createGlobalStyle, ThemeProvider } from 'styled-components'

const GlobalStyle = createGlobalStyle`
  body {
    color: ${props => (props.whiteColor ? 'white' : 'black')};
    font-family: ${props => props.theme.fontFamily};
  }
`

// later in your app


  
     {/* example of other top-level stuff */}
    
  

---

实例测试：

style.js :

import {createGlobalStyle} from 'styled-components';

export const GlobalStyle = createGlobalStyle`
    body {
        background: blue;
    }
`;

App.js:

import React, { Component,Fragment } from 'react';
import Header from "./common/header";
//导入样式文件
import {GlobalStyle} from "./style";

class App extends Component {
    render() {
        return (
            
                
                    

            
        )
    }
}

export default App;

做的不好，仅供参考！