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ES6 Iterator et pro... ansa (5)

2024-07-12

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Iterator lineamenta:

  • Interface coniungitur: Utrum ordinata, chorda vel obiectum consuetudinis, dummodo defaltam iteratorem habeant, uti potes pro ... ansa percurrendi.
  • Objecta Iterable: Objecta cum attributo iterabilia considerantur. [Symbol.iterator] modus est qui iterator redit.
  • Iterator obiectum: iterator est obiectum cum altera methodo quae redit rem continens valorem et proprietates acta. valor est valor iterationis currentis, et factum est valorem Boolean significans utrum iteratio compleatur.

pro ... loop habet:

  • Syntaxis concisa: Utere ad ... iterandum per unumquodque elementum in obiecto iterabili sine scriptura addita iteratione logica.
  • Automatic iteratio: nam ... ansa sponte vocat modum proximum iteratoris ad valorem proximum obtinendum.
  • Exceptio pertractatio: Experimentum uti potes... capere in pro... ansa ad capiendas exceptiones in processu iterationis coniectas.

I: usus est ... percurrere ordinata

let numbers = [1, 2, 3, 4, 5];

for (let number of numbers) {
    console.log(number); // 依次输出 1 到 5
}
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II: usus est ... ad percurrendi filum

let str = "Hello";

for (let char of str) {
    console.log(char); // 依次输出 'H', 'e', 'l', 'l', 'o'
}
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3: Custom iterator

let myIterable = {
    [Symbol.iterator]: function* () {
        yield 1;
        yield 2;
        yield 3;
    }
};

for (let value of myIterable) {
    console.log(value); // 依次输出 1, 2, 3
}
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4: Utere pro de consuetudine iteratorum

function* numberIterator(max) {
    let current = 1;
    while (current <= max) {
        yield current++;
    }
}

for (let number of numberIterator(5)) {
    console.log(number); // 依次输出 1 到 5
}
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5: Usus ad excipiendas exceptiones

let iterable = [1, 2, 3, 4, 'error', 6];

for (let item of iterable) {
    try {
        if (typeof item === 'string') {
            throw new Error('Invalid value');
        }
        console.log(item * 2); // 依次输出 2, 4, 6, 8
    } catch (e) {
        console.error(e.message); // 输出:Invalid value
    }
}
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VI: usus Array.from convertere iterabilia obiecta vestit

let str = "Iterator";

let arrayFromIterable = Array.from(str);
console.log(arrayFromIterable); // 输出:['I', 't', 'e', 'r', 'a', 't', 'o', 'r']
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Notice

convenientiam:pro... ansarum sustentantur in navigatoribus modernis et Node.js, sed nonnullae culturae JavaScript antiquiores non possunt.
perficientur: Pro amplis collectionibus, a for... ansa non potest esse tam efficax quam traditum pro ansa, quia unaquaeque iteratio requirit vocationem ad modum proxime iteratoris.

7: Symbol.iterator ordinatae

let arr = [1, 2, 3];

// 数组是可迭代对象,具有默认的 Symbol.iterator 属性
let iterator = arr[Symbol.iterator]();

console.log(iterator.next()); // { value: 1, done: false }
console.log(iterator.next()); // { value: 2, done: false }
console.log(iterator.next()); // { value: 3, done: false }
console.log(iterator.next()); // { value: undefined, done: true }
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8: Symbol.iterator chordae

let str = "abc";

// 字符串也是可迭代对象
let strIterator = str[Symbol.iterator]();

console.log(strIterator.next()); // { value: "a", done: false }
console.log(strIterator.next()); // { value: "b", done: false }
console.log(strIterator.next()); // { value: "c", done: false }
console.log(strIterator.next()); // { value: undefined, done: true }
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9: Manually use symbol.iterator

let myObj = {
    items: [3, 5, 7],
    [Symbol.iterator]: function* () {
        for (let item of this.items) {
            yield item * 2; // 迭代器返回值的两倍
        }
    }
};

let iterator = myObj[Symbol.iterator]();

console.log(iterator.next()); // { value: 6, done: false }
console.log(iterator.next()); // { value: 10, done: false }
console.log(iterator.next()); // { value: 14, done: false }
console.log(iterator.next()); // { value: undefined, done: true }
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