如何在 Typescript 中分隔数组

Question

我正在使用 Angular2 创建一个应用程序，并且我有很多方。

const PARTIES: Party[] = [
  { id: 1, title: "Main Event", description: "The biggest, most extravagant event in the last 10,000,000 years." },
  { id: 2, title: "Secondary Event", description: "The not as biggest, less extravagant event in the last 10,000,000 years." },
  { id: 3, title: "Another Event", description: "N/A" },
  { id: 4, title: "Another Event", description: "N/A" },
  { id: 5, title: "Another Event", description: "N/A" },
  { id: 6, title: "Another Event", description: "N/A" },
  { id: 7, title: "Another Event", description: "N/A" },
  { id: 8, title: "Another Event", description: "N/A" },
  { id: 9, title: "Another Event", description: "N/A" },
  { id: 10, title: "Another Event", description: "N/A" }
];

在保留原始数组的同时，我想将这个数组分成 3 段。

在普通的旧 JavaScript 中，我会使用以下内容。

var chunk_size = 3;
var arr = PARTIES;
var groups = arr.map(function(e,i){
    return i%chunk_size===0 ? arr.slice(i,i+chunk_size) : null;
})
.filter(function(e){ return e; });
PARTIES = groups

但是，我使用的是 TypeScript。是否有任何可能的方法来执行我尝试使用 TypeScript 实现的目标？

Answer 1

您的 JavaScript 代码：

var chunk_size = 3;
var arr = PARTIES;
var groups = arr.map(function(e,i){
    return i%chunk_size===0 ? arr.slice(i,i+chunk_size) : null;
})
.filter(function(e){ return e; });
PARTIES = groups

不正确。如果它是 它将是有效的 TypeScript 并且它会正常工作，因为 JavaScript 是 TypeScript https://basarat.gitbooks.io/typescript/content/docs/why-typescript.html :)

修复

以下是一个工作示例：

const PARTIES = [
  { id: 1, title: "Main Event", description: "The biggest, most extravagant event in the last 10,000,000 years." },
  { id: 2, title: "Secondary Event", description: "The not as biggest, less extravagant event in the last 10,000,000 years." },
  { id: 3, title: "Another Event", description: "N/A" },
  { id: 4, title: "Another Event", description: "N/A" },
  { id: 5, title: "Another Event", description: "N/A" },
  { id: 6, title: "Another Event", description: "N/A" },
  { id: 7, title: "Another Event", description: "N/A" },
  { id: 8, title: "Another Event", description: "N/A" },
  { id: 9, title: "Another Event", description: "N/A" },
  { id: 10, title: "Another Event", description: "N/A" }
];

var chunk_size = 3;
const groups = PARTIES.map(function(e,i){
    return i%chunk_size===0 ? PARTIES.slice(i,i+chunk_size) : null;
})
.filter(x=>!!x)

console.log(groups);

关于修复的一些说明：

• 无法重新分配常量。所以你不能重新分配给 PARTIES
• PARTIES ([]) 的类型与 groups ([][]) 的类型不同，所以无论如何您都不想指定它
• 最好在filter 中使用真boolean 而不是真/假检查。更多：https://basarat.gitbooks.io/typescript/content/docs/tips/truthy.html