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问题描述

我看到以下情况很好:

const Tab = connect( mapState, mapDispatch )( Tabs );
export default Tab;

然而,这是不正确的:

export default const Tab = connect( mapState, mapDispatch )( Tabs );

但这很好:

export default Tab = connect( mapState, mapDispatch )( Tabs );

可以解释为什么 const 导出默认无效?这是不必要的补充吗?声明为导出默认值的任何内容都假定为 const 或类似的?

Can this be explained please why const is invalid with export default? Is it an unnecessary addition & anything declared as export default is presumed a const or such?

推荐答案

const 就像,( VariableStatement,声明),用于在块中定义标识符。

const is like let, it is a LexicalDeclaration (VariableStatement, Declaration) used to define an identifier in your block.

您正在尝试将其与默认关键字混合, 需要 HoistableDeclaration,ClassDeclaration AssignmentExpression 跟随它。

You are trying to mix this with the default keyword, which expects a HoistableDeclaration, ClassDeclaration or AssignmentExpression to follow it.

因此它是 SyntaxError

如果你想要 const 你需要提供标识符,而不是使用 default

If you want to const something you need to provide the identifier and not use default.

export 本身接受 VariableStatement 声明 to it'是的。

export by itself accepts a VariableStatement or Declaration to it's right.

AFAIK导出本身不应该在当前范围内添加任何东西。

AFAIK the export in itself should not add anything to your current scope.

Tab 成为 AssignmentExpression ,因为它的名称为 default

Tab becomes an AssignmentExpression as it's given the name default

这里 Tab = connect( mapState,mapDispatch)(Tabs); AssignmentExpression

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07-23 07:38