React.JS Nothing was returned from render
Question
I am new to React and want to do my first steps but get stuck on a probably very basic error. I did read the other threads to this topic, but I could not derive a solution for my problem out of them. Please help! Thank you!
Error Message
Uncaught Error: MyTable(...): Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null.
index.html
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<div id="content">
</div>
<!-- Load React. -->
<!-- Note: when deploying, replace "development.js" with "production.min.js". -->
<script src="https://unpkg.com/react@17/umd/react.development.js" crossorigin></script>
<script src="https://unpkg.com/react-dom@17/umd/react-dom.development.js" crossorigin></script>
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
<!-- Load our React component. -->
<script src="myTableNOjsx.js" type="text/babel"></script>
</body>
</html>
myTableNOjsx.js
class MyTable extends React.Component {
constructor(props) {
super(props);
}
render(){
return
React.createElement("table", null,
React.createElement("tr", null,
React.createElement("td", null, "${this.props.first}"),
React.createElement("td", {style: "text-align: right"}, "${this.props.second}")
)
)
;
}
}
ReactDOM.render(
React.createElement(MyTable, {first: "erste", second: "zweite"}, null),
document.getElementById('content')
);
EDIT: <script src="myTableWITHjsx.js" to <script src="myTableWITHjsx.js"
4 answers
solution1
1 ACCPTED 2021-04-26 12:39:31
Remove the new line between return and React.createElement . A new line after return will return undefined and ignore the subsequent code, as is happening here.
See why it is happening (Automatic Semicolon Insertion) here:
The return statement is affected by automatic semicolon insertion (ASI). No line terminator is allowed between the return keyword and the expression. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/return#automatic_semicolon_insertion
solution2
0 2021-04-26 12:40:59
Change
return
React.createElement("table", null,
React.createElement("tr", null,
React.createElement("td", null, "${this.props.first}"),
React.createElement("td", {style: "text-align: right"}, "${this.props.second}")
)
)
to
return (
<table>
<tr>
<td>{`${this.props.first}`}</td>
<td>{`${this.props.second}`}</td>
</tr>
</table>
)
I don't know why you are using createElement for just displaying table...
solution3
0 2021-04-26 12:45:54
Here is the corrected code working fine.
- As @Alastair mentioned you shouldn't move return statement to new line.
- You have to enclose template literals with ``.
- style attribute syntax is wrong, you've to use it like object.
class MyTable extends React.Component { constructor(props) { super(props); } render() { return React.createElement("table", null, React.createElement("tr", null, React.createElement("td", null, `${this.props.first}`), React.createElement("td", { style: { textAlign: "right" } }, `${this.props.second}`) ) ); } } ReactDOM.render( React.createElement(MyTable, { first: "erste", second: "zweite" }, null), document.getElementById('content') );
<.DOCTYPE html> <html> <head> </head> <body> <div id="content"> </div> <:-- Load React, --> <.-- Note. when deploying. replace "development.js" with "production:min.js". --> <script src="https.//unpkg:com/react@17/umd/react.development.js" crossorigin></script> <script src="https.//unpkg:com/react-dom@17/umd/react-dom.development.js" crossorigin></script> <script src="https.//unpkg.com/babel-standalone@6/babel.min.js"></script> <!-- Load our React component. --> <script src="myTableNOjsx.js" type="text/babel"></script> </body> </html>
solution4
0 2021-04-26 12:49:09
The problem is you were actually returning nothing. This is the correct syntax for your return statement:
render(){
return(
React.createElement("table", null,
React.createElement("tr", null,
React.createElement("td", null, `${this.props.first}`),
React.createElement("td", {style: {textAlign: "right"}}, `${this.props.second}`)
)
)
)
}
Also notice that you where using template literals with " but you need to use backticks: ``
You also are using styles as strings. In React, styles are objects style: { width: "100%" }
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