我有一个这样定义的枚举:
export enum GoalProgressMeasurements {
Percentage = 1,
Numeric_Target = 2,
Completed_Tasks = 3,
Average_Milestone_Progress = 4,
Not_Measured = 5
}
然而，我希望它被表示为一个对象数组/列表从我们的API如下:
[{id: 1, name: 'Percentage'},
{id: 2, name: 'Numeric Target'},
{id: 3, name: 'Completed Tasks'},
{id: 4, name: 'Average Milestone Progress'},
{id: 5, name: 'Not Measured'}]
是否有简单和本地的方法来做到这一点，或者我必须构建一个函数，将枚举转换为int和字符串，并将对象构建为数组?
当前回答
另一种方法是
export const GoalNames = {
[GoalProgressMeasurements.Percentage] = 'Percentage',
[GoalProgressMeasurements.Numeric_Target] = 'Numeric Target',
[GoalProgressMeasurements.Completed_Tasks] = 'Completed Tasks',
[GoalProgressMeasurements.Average_Milestone_Progress] = 'Average Milestone Progress',
[GoalProgressMeasurements.Not_Measured] = 'Not Measured'
}
你可以调用:
const name = GoalNames[goalEnumVal];
其他回答
只有一句话:
Object.entries(GoalProgressMeasurements).map(([key, value]) => ({id: key, value: value}))
我不认为顺序是可以保证的，否则就很容易切片Object的后半部分。条目的结果和映射来自那里。
上述答案的唯一(非常小的)问题是
字符串和数字之间有很多不必要的类型转换。 当一次迭代同样干净有效时，条目将迭代两次。
type StandardEnum = { [id: string]: number | string; [nu: number]: string;}
function enumToList<T extends StandardEnum> (enm: T) : { id: number; description: string }[] {
return Object.entries(enm).reduce((accum, kv) => {
if (typeof kv[1] === 'number') {
accum.push({ id: kv[1], description: kv[0] })
}
return accum
}, []) // if enum is huge, perhaps pre-allocate with new Array(entries.length / 2), however then push won't work, so tracking an index would also be required
}
枚举是运行时存在的真实对象。所以你可以这样反向映射:
let value = GoalProgressMeasurements.Not_Measured;
console.log(GoalProgressMeasurements[value]);
// => Not_Measured
基于此，您可以使用以下代码:
export enum GoalProgressMeasurements {
Percentage = 1,
Numeric_Target = 2,
Completed_Tasks = 3,
Average_Milestone_Progress = 4,
Not_Measured = 5
}
let map: {id: number; name: string}[] = [];
for(var n in GoalProgressMeasurements) {
if (typeof GoalProgressMeasurements[n] === 'number') {
map.push({id: <any>GoalProgressMeasurements[n], name: n});
}
}
console.log(map);
参考:https://www.typescriptlang.org/docs/handbook/enums.html
如果你使用的是ES8
只有在这种情况下，它才会工作得很好。它会给你给定枚举的值数组。
enum Colors {
WHITE = 0,
BLACK = 1,
BLUE = 3
}
const colorValueArray = Object.values(Colors); //[ 'WHITE', 'BLACK', 'BLUE', 0, 1, 3 ]
你会得到这样的colorValueArray ['WHITE'， 'BLACK'， 'BLUE'， 0,1,3]。所有的键都在数组的前半部分，所有的值都在数组的后半部分。
甚至这种枚举也可以正常工作
enum Operation {
READ,
WRITE,
EXECUTE
}
但是这种解决方案不适用于这样的异构枚举
enum BooleanLikeHeterogeneousEnum {
No = 0,
Yes = "YES",
}
function enumKeys(_enum) {
const entries = Object.entries(_enum).filter(e => !isNaN(Number(e[0])));
if (!entries.length) {
// enum has string values so we can use Object.keys
return Object.keys(_enum);
}
return entries.map(e => e[1]);
}
