typescript 打字稿数组映射返回对象
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Typescript Array Map Return Object
提问by Dan Grahn
I have the following code.
我有以下代码。
array.map(val => { return {
key1: val.key1,
key2: val.key2
}});
Is there any way to reduce the code to something like this?
有没有办法将代码减少到这样的程度？
array.map(val => {
key1: val.key1,
key2: val.key2
});
回答by Titian Cernicova-Dragomir
If you put it in parenthesis the compiler will treat it as an object literal not a code block:
如果将它放在括号中，编译器会将其视为对象文字而不是代码块：
array.map(val => ({
key1: val.key1,
key2: val.key2
}));
A type assertion also works if you have an interface for the object literal (but is not as type safe):
如果您有对象文字的接口（但不是类型安全的），则类型断言也有效：
interface IKeys { key1: string; key2: string }
array.map(val => <IKeys>{
key1: val.key1,
key2: val.key2
});
回答by ellockie
As an update to @Titian Cernicova-Dragomir's answer above, it's worth mentioning the asoperator(for Type Assertion), especially useful when working with React's TSX(JSX) files, equivalent to the <Type>syntax:
作为上面@Titian Cernicova-Dragomir 回答的更新，值得一提的是as操作符（用于类型断言），在处理 React 的 TSX(JSX) 文件时特别有用，相当于<Type>语法：
interface IKeys { key1: string; key2: string }
// notice the parentheses, to avoid confusion with a block scope
array.map(val => ({
key1: val.key1,
key2: val.key2
} as IKeys));
It was introduced because the angle brackets syntax (<ComponentOrElement>) is reserved for components / JSX Elements.
引入它是因为尖括号语法 ( <ComponentOrElement>) 是为组件/ JSX 元素保留的。
