Javascript对象解构 [英] Javascript object destructuring
问题描述
为什么在使用新的es6破解语法时无效?
Why is this not valid when using the new es6 destructuring syntax
var a, b, c;
{a, b, c } = {a:1, b:2, c:3};
当这是:
var {a, b, c } = {a:1, b:2, c:3};
console.log(a, ' ', b, ' ',c);
所以这样:
var a = 1;
var b = 3;
[a, b] = [b, a];
我读过 MDN文档,我看到没有提到我正在尝试的语法,我认为必须有一个很好的理由,我只是想了解为什么。
I had a read of the MDN documentataion and I see no mention of the syntax I'm attempting and I assume there must be a good reason, I'm just trying to understand why.
推荐答案
在你的例子中,第一个 {
是不明确的,解析器将它解释为块的开头。虽然 {a,b,c}
是一个有效的块,但以下赋值运算符无效。
In your example, the first {
is ambiguous and the parser will interpret it as the beginning of a block. While {a, b, c}
is a valid block, the following assignment operator is not valid.
括号中的所有内容都将正确解析:
Wrap everything in parenthesis and it will parse correctly:
({a, b, c} = {a:1, b:2, c:3});
这与有一个对象字面本身(无论什么原因):
This is similar to having an object literal by itself (for whatever reasons):
{"a": 42} // parse error
({"a": 42}) // works
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