Javascript 解析错误：意外的标记，预期的“，”
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Parsing error: Unexpected token, expected ","
提问by null
I have below code in react js.
我在react js中有以下代码。
class Posts extends Component {
render() {
return (
{console.log('test')}
);
}
}
After running this code I get error which is
运行此代码后，我收到错误
Parsing error: Unexpected token, expected ","
8 | return (
> 9 | {console.log('test')}
| ^
10 | );
11 | }
12 | }
UPDATE
更新
wrapping it up with parent tag returns the same error
用父标签包装它会返回相同的错误
> 9 | <div>
| ^
10 | {console.log('nothing')}
11 | </div>
UPDATE
更新
here is the whole class
这是全班同学
import React, { Component } from 'react';
import { connect } from 'react-redux';
class Post extends Component {
render() {
return (
<div>
{console.log('test')}
</div>
);
}
}
const mapStateToProps = (state) => {
return {
posts: state
}
};
export default Post;
回答by maxm
You always need to have a wrapping parent JSX tag when returning jsx. Since you don't have any jsx tags it's just invalid javascript. Should be:
返回 jsx 时，您始终需要有一个包装父 JSX 标记。由于您没有任何 jsx 标签，因此它只是无效的 javascript。应该：
class Posts extends Component {
render() {
return console.log('test')
}
}
or if you want the jsx
或者如果你想要 jsx
class Posts extends Component {
render() {
return (
<div>
{console.log('test')}
</div>
)
}
}
edit (2020-1-19)
编辑 (2020-1-19)
jsx now supports empty tags for parent closures:
jsx 现在支持父闭包的空标签：
class Posts extends Component {
render() {
return (
<>
{console.log('test')}
</>
)
}
}
回答by Mehrdad Masoumi
in react js You have to put a value in the attr.
在 react js 中，你必须在 attr 中放置一个值。
an example that works
一个有效的例子
<option selected={this.props.info.gender == 0 ? 'selected' : ''} value='0'>men</option>
<option selected={this.props.info.gender == 1 ? 'selected' : ''} value='1'>female</option>
not working
不工作
<option {this.props.info.gender == 0 ? 'selected' : ''} value='0'>men</option>
<option {this.props.info.gender == 1 ? 'selected' : ''} value='1'>female</option>
回答by Andrey Grek
@Mehrdad Masoumi, have a big mistake, this true:
@Mehrdad Masoumi，有一个大错误，这是真的：
<option selected={this.props.info.gender == **1** ? 'selected' : ''} value='**1**'>men</option>
<option selected={this.props.info.gender == **0** ? 'selected' : ''} value='**0**'>female</option>
回答by Ezekiel Saturday
@null use a callback that returns console.log.
@null 使用返回 console.log 的回调。
Asin
阿信
() => console.log('test')
回答by Mehrdad Masoumi
mapStateToProps used by connect method of redux add console.log Before the return method
redux的connect方法使用的mapStateToProps在return方法前添加console.log
