javascript - Line break within arrow function throws “Uncaught SyntaxError: Unexpected token `=>`”

Question

I’m getting the error “Uncaught SyntaxError: Unexpected token =>” on my console when I put the e parameter in parentheses and then use an ES6 arrow function. However, there’s no error when I remove the parameter from the parentheses. Should the parameter not have parentheses?

document.querySelector("#book-form").addEventListener("submit", (e) 
=> {
  // …
});

Answer 1

Arrow functions cannot have a newline between the parameters and the =>:

14.2 Arrow Function Definitions

ArrowFunction[In, Yield, Await]:

• ArrowParameters [?Yield, ?Await] [no LineTerminator here] => ConciseBody

Either remove the newline, or put it somewhere else. You could also use a named function instead, eg:

const submitHandler = (e) => {
  // ...
};
document.querySelector("#book-form").addEventListener("submit", submitHandler);