箭头函数内的换行符引发“未捕获的SyntaxError:意外的令牌'=>`" [英] Line break within arrow function throws “Uncaught SyntaxError: Unexpected token `=>`”

问题描述

当我将e参数放在括号中并使用ES6箭头功能时，在控制台上出现错误未捕获的SyntaxError:意外的令牌=>" .但是，当我从括号中删除参数时没有错误.该参数应该没有括号吗?

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) 
=> {
  // …
});

推荐答案

箭头函数在参数和=>之间不能有换行符:

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

14.2箭头功能定义

ArrowFunction [输入，收益，等待]:

ArrowFunction[In, Yield, Await]:

• ArrowParameters [?Yield，?Await] [此处没有LineTerminator] => ConciseBody

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

删除换行符，或将其放在其他位置.您也可以改用命名函数，例如:

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);

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