Learn how to use JS's built-in iterable objects effectively

In-depth understanding of how to use JS built-in iterable objects

In JavaScript, an iterable object refers to an object that implements the Symbol.iterator method. These objects can be iterated over using a for...of loop, or manipulated using other iterator methods. This article will provide an in-depth understanding of how to use JS's built-in iterable objects and give specific code examples.

1. Array (array)

Array is the most common iterable object in JavaScript. We can use a for...of loop to iterate through each element in the array, or use the array's forEach method to iterate.

Code example:

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

// 使用for...of循环遍历数组
for (let num of arr) {
  console.log(num);
}

// 使用数组的forEach方法遍历数组
arr.forEach(function(num) {
  console.log(num);
});

2. String (String)

Strings are also iterable objects in JavaScript. We can iterate through each character in the string through a for...of loop.

Code example:

let str = "hello";

// 使用for...of循环遍历字符串
for (let char of str) {
  console.log(char);
}

3. Set (set)

Set is a collection of non-repeating elements and an iterable object. We can use a for...of loop to iterate through each element in the Set.

Code example:

let set = new Set([1, 2, 3]);

// 使用for...of循环遍历Set
for (let num of set) {
  console.log(num);
}

4. Map (mapping)

Map is a collection of key-value pairs and an iterable object. We can use a for...of loop to iterate through each key-value pair in the Map.

Code example:

let map = new Map();
map.set('key1', 'value1');
map.set('key2', 'value2');

// 使用for...of循环遍历Map
for (let [key, value] of map) {
  console.log(key, value);
}

5. Generator (generator)

Generator is a function that can produce a series of values ​​and is also an iterable object. We can use a for...of loop to iterate through the sequence of values ​​generated by the Generator.

Code example:

function* generator() {
  yield 1;
  yield 2;
  yield 3;
}

// 通过Generator生成值序列
let gen = generator();
for (let num of gen) {
  console.log(num);
}

In addition to the above built-in iterable objects, there are some other objects that are also iterable, such as TypedArray, NodeList, etc. We can iterate over them using the same method.

Summary:
In JavaScript, we can traverse various iterable objects through for...of loops, or use other iterator methods to operate. Mastering the use of these built-in iterable objects will make us more efficient and flexible when writing JavaScript code.

I hope this article can be helpful to readers. If you have any questions or suggestions, please leave a message for discussion. Thanks!

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