Solve the Invalid DOM property `for` warning in React
To fix the React.js warning “Invalid DOM property for. Did you mean tmlFor“. Use htmlForthe for property because for is a reserved word in JavaScript.
Below is an example of how the warning is generated.
export default function App() {
// ⛔️ Warning: Invalid DOM property `for`. Did you mean `htmlFor`?
return (
<div>
<label for="firstName">First Name</label>
<input id="firstName" type="text" />
</div>
);
}
The problem in the code example is that we use forthe attribute to labelmatch the tag to the input, but foris a reserved word in JavaScript.
To eliminate the warning, we have to use
htmlForinstead offor.
export default function App() {
return (
<div>
<label htmlFor="firstName">First Name</label>
<input id="firstName" type="text" />
</div>
);
}
htmlForProperty is not React.jsfor specific, it is also used in browsers to set properties programmatically .
If we have some accessibility linting rules, we might have to
labelwrap ourinput</head> tag with .
export default function App() {
return (
<div>
<label htmlFor="firstName">
First Name
<input id="firstName" type="text" />
</label>
</div>
);
}
The reason we have to use in React htmlForis because the for keyword is a reserved word - it is used for the for loop.
This is also classNamethe reason why properties are used instead of classes. classThis word is reserved as it is used to declare ES6 classes.
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