为什么在ES6箭头函数中`throw`无效？ [英] Why is `throw` invalid in an ES6 arrow function?

问题描述

）=>投掷42

我知道我可以通过以下方式解决：

 （）=> {throw 42}; 
  

解决方案

如果不使用块（ {} ）作为箭头功能，身体必须是 表达式 ：

  ArrowFunction：
 ArrowParameters [no LineTerminator here] => ConciseBody 
 
 ConciseBody：
 [lookahead≠{] AssignmentExpression 
 {FunctionBody} 
  

但是 throw 是一个 语句 ，而不是表达式。

---

理论上

 （）=>扔x 
  

相当于

 （）=> {return throw x; 
  

这也不是有效的。

I'm just looking for a reason as to why this is invalid:

() => throw 42;

I know I can get around it via:

() => {throw 42};

解决方案

If you don't use a block ({}) as body of an arrow function, the body must be an expression:

ArrowFunction:
    ArrowParameters[no LineTerminator here] => ConciseBody

ConciseBody:
    [lookahead ≠ { ] AssignmentExpression
    { FunctionBody }

But throw is a statement, not an expression.

---

In theory

() => throw x;

is equivalent to

() => { return throw x; }

which would not be valid either.

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