ECMAScript6 新特性范例大全(2)

迭代器是一个比数组更动态的类型。

let infinite = { [Symbol.iterator]() { let c = 0; return { next() { c++; return { done: false, value: c } } } } } console.log("start"); for (var n of infinite) { // truncate the sequence at 1000 if (n > 10) break; console.log(n); }

结果：

"start" -> start n -> 1 n -> 2 n -> 3 n -> 4 n -> 5 n -> 6 n -> 7 n -> 8 n -> 9 n -> 10

使用Typescript，我们可以看到它接口的样子：

interface IteratorResult { done: boolean; value: any; } interface Iterator { next(): IteratorResult; } interface Iterable { [Symbol.iterator](): Iterator } 生成器（Generators）

生成器创建迭代器，并且比迭代器更具动态性。他们不必以相同的方式跟踪状态 并不支持 done 的概念。

var infinity = { [Symbol.iterator]: function*() { var c = 1; for (;;) { yield c++; } } } console.log("start") for (var n of infinity) { // truncate the sequence at 1000 if (n > 10) break; console.log(n); }

结果：

"start" -> start n -> 1 n -> 2 n -> 3 n -> 4 n -> 5 n -> 6 n -> 7 n -> 8 n -> 9 n -> 10

使用Typescript 再次显示接口：

interface Generator extends Iterator { next(value?: any): IteratorResult; throw(exception: any); }

一个产量的例子*

function* anotherGenerator(i) { yield i + 1; yield i + 2; yield i + 3; } function* generator(i) { yield i; yield* anotherGenerator(i); yield i + 10; } var gen = generator(10); console.log(gen.next().value); console.log(gen.next().value); console.log(gen.next().value); console.log(gen.next().value); console.log(gen.next().value);

结果：

gen.next().value -> 10 gen.next().value -> 11 gen.next().value -> 12 gen.next().value -> 13 gen.next().value -> 20 Unicode

ES6 为Unicode 提供了更好的支持。

var regex = new RegExp('\u{61}', 'u'); console.log(regex.unicode) console.log("\uD842\uDFD7") console.log("\uD842\uDFD7".codePointAt())

结果：

regex.unicode -> true "" -> "".codePointAt() -> 134103 模块和模块加载器

原生支持模块。

import defaultMember from "module-name"; import * as name from "module-name"; import { member } from "module-name"; import { member as alias } from "module-name"; import { member1 , member2 } from "module-name"; import { member1 , member2 as alias2 , [...] } from "module-name"; import defaultMember, { member [ , [...] ] } from "module-name"; import defaultMember, * as name from "module-name"; import "module-name"; export { name1, name2, …, nameN }; export { variable1 as name1, variable2 as name2, …, nameN }; export let name1, name2, …, nameN; // also var export let name1 = …, name2 = …, …, nameN; // also var, const export expression; export default expression; export default function (…) { … } // also class, function* export default function name1(…) { … } // also class, function* export { name1 as default, … }; export * from …; export { name1, name2, …, nameN } from …; export { import1 as name1, import2 as name2, …, nameN } from …; Set