React Native - how to trim a string

The problem is in your setEmail call and the ES6 syntax that you are using. When you do:

email => this.setEmail({email})

The transpiler transforms it into the following:

email => this.setEmail({email: email})

Which of course is an object.

Then, inside the function, you are trying to apply the trim function to an object, which of course results in failure. Try this instead:

email => this.setEmail(email)

You can read more on the ES6 syntax for object literals here.

In case the string you want to trim is a state and you want to trim the spaces, but not to render the whole page, then you can do it directly as following:

this.state.text = this.state.text.trim()