javascript - WebStorm JavaScript 解构赋值

Question

WebStorm 中以下有效的 ES6:

let {a,b} = {a:0,b:0};
{a,b} = {a:2,b:4};

在第二个等号处显示错误:“预期表达式”。显然 JavaScript 设置设置为 ES6。

顺便说一下，添加括号可以消除错误:

let {a,b} = {a:0,b:0};
({a,b} = {a:2,b:4});

这是一个错误还是 ES6 的一部分？ Node 编译器似乎对第一个版本(没有括号)没有问题，因此它似乎不是标准的一部分。

Answer 1

这不是一个错误，这就是 ExpressionStatement是:

NOTE An ExpressionStatement cannot start with a U+007B (LEFT CURLY BRACKET) because that might make it ambiguous with a Block. An ExpressionStatement cannot start with the function or class keywords because that would make it ambiguous with a FunctionDeclaration, a GeneratorDeclaration, or a ClassDeclaration. An ExpressionStatement cannot start with async function because that would make it ambiguous with an AsyncFunctionDeclaration. An ExpressionStatement cannot start with the two token sequence let [ because that would make it ambiguous with a let LexicalDeclaration whose first LexicalBinding was an ArrayBindingPattern.