You dont have context (this
is not bound to your function).
You can fix that using one of the following:
First, bind this in constructor
constructor(props) {
super(props);
this.onFormSubmit = this.onFormSubmit.bind(this);
}
Second, use arrow functions
onFormSubmit = (event) => {
...
}
Third, use autobind-decorator or the like
@boundMethod
onFormSubmit(event) {
...
}
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