Form validation for username and Email in java script

I'm trying to validate the value in my name element and email address element.
but the below code is not providing the proper validation and my code is still jumping to my php file with wrongs inputs in it.
can anybody please provide me some guidance on this?
```
var letters = /^[A-Za-z]+$/;
var mailformat = ^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$;

if( document.addform.First_name.value.match(letters)) {
return true;
}
else {
alert( "Username must have alphabet characters only" );
document.addform.First_name.focus() ;
return false;
}
if( document.addform.email.value.match(mailformat) ) {
return true;
}
else {
alert( "You have entered an invalid email address!" );
document.addform.email.focus() ;
return false;
}
```

You need to return true if both conditions are met, not just one of them.

```
function validateFormInput () {
let yourUsernameRegEx = new RegExp(...);
let yourMailRegEx = new RegExp(...);

if (!document.addform.First_name.value.match(yourUsernameRegEx)) {
// Other code here (alerts, popups, etc.) ...

return false;
}

if (!document.addform.email.value.match(yourMailRegEx)) {
// Other code here (alerts, popups, etc.) ...

return false;
}

return true;
}
```