TypeScript中的array.groupBy [英] array.groupBy in TypeScript
问题描述
基本数组类具有 .map
, .forEach
, .filter
和 .reduce
,但是 .groupBy
却明显缺席,无法执行
The basic array class has .map
, .forEach
, .filter
, and .reduce
, but .groupBy
i noticably absent, preventing me from doing something like
const MyComponent = (props:any) => {
return (
<div>
{
props.tags
.groupBy((t)=>t.category_name)
.map((group)=>{
[...]
})
}
</div>
)
}
我最终自己实现了一些东西:
I ended up implementing something myself:
class Group<T> {
key:string;
members:T[] = [];
constructor(key:string) {
this.key = key;
}
}
function groupBy<T>(list:T[], func:(x:T)=>string): Group<T>[] {
let res:Group<T>[] = [];
let group:Group<T> = null;
list.forEach((o)=>{
let groupName = func(o);
if (group === null) {
group = new Group<T>(groupName);
}
if (groupName != group.key) {
res.push(group);
group = new Group<T>(groupName);
}
group.members.push(o)
});
if (group != null) {
res.push(group);
}
return res
}
现在我可以做
const MyComponent = (props:any) => {
return (
<div>
{
groupBy(props.tags, (t)=>t.category_name)
.map((group)=>{
return (
<ul key={group.key}>
<li>{group.key}</li>
<ul>
{
group.members.map((tag)=>{
return <li key={tag.id}>{tag.name}</li>
})
}
</ul>
</ul>
)
})
}
</div>
)
}
很漂亮很好,但是我需要包装列表而不是仅仅能够聊天就太糟糕了
Works pretty well, but it is too bad that I need to wrap the list rather than just being able to chain method calls.
是否有更好的解决方案?
Is there a better solution?
推荐答案
您可以在应用程序中将函数添加到数组原型中(请注意一些建议不要这样做:为什么扩展本机对象是一种不好的做法?):
you could add the function to the array prototype in your app (note some don't recomend this: Why is extending native objects a bad practice?):
Array.prototype.groupBy = function(/* params here */) {
let array = this;
let result;
/* do more stuff here*/
return result;
};
然后在打字稿中创建一个界面,如下所示:
Then create an interface in typescript like this:
.d.ts版本:
interface Array<T>
{
groupBy<T>(func:(x:T) => string): Group<T>[]
}
或在常规ts文件中:
declare global {
interface Array<T>
{
groupBy<T>(func:(x:T) => string): Group<T>[]
}
}
然后您可以使用:
props.tags.groupBy((t)=>t.category_name)
.map((group)=>{
[...]
})
这篇关于TypeScript中的array.groupBy的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!