How does Jquery realize conversion between Map objects, arrays, and objects

In JQuery, we often encounter situations where we need to traverse arrays or objects. The use of Map objects can greatly facilitate our traversal operations. This article will explain the use of Map objects in JQuery and the methods of converting Map objects to arrays and objects.

1. The use of Map objects in JQuery

Map objects are similar to "dictionaries" or "hash tables" in other programming languages ​​and are used to store key-value pairs. The Map object in JQuery mainly consists of two methods: set and get.

1. set method

The set method is used to add key-value pairs to the Map object. The syntax is as follows:

Map.set(key, value);

Among them, key represents the key to be added, and value represents the value to be added. For example:

var myMap = new Map();
myMap.set("apple", 2);
myMap.set("orange", 3);

At this time, there are two key-value pairs in myMap, namely "apple" and "orange".

2. get method

The get method is used to obtain the value of the specified key from the Map object. The syntax is as follows:

Map.get(key);

Among them, key represents the key to obtain the value. For example:

var myMap = new Map();
myMap.set("apple", 2);
myMap.set("orange", 3);
var appleNum = myMap.get("apple"); // appleNum等于2

2. Conversion between Map objects and arrays and objects

Map objects are very convenient to use in JQuery, but in actual development we will also encounter the need to convert Map objects A scene that is an array or object. Here's how to implement these conversions.

1. Map object is converted to an array

Map object is converted to an array, which can be achieved through the spread operator in ES6. The syntax is as follows:

[...Map];

For example:

var myMap = new Map();
myMap.set("apple", 2);
myMap.set("orange", 3);
var myArray = [...myMap];
console.log(myArray); // [["apple", 2], ["orange", 3]]

2. Map object is converted to object

Map object is converted to object by using the Object.fromEntries method . The syntax is as follows:

Object.fromEntries(Map);

For example:

var myMap = new Map();
myMap.set("apple", 2);
myMap.set("orange", 3);
var myObj = Object.fromEntries(myMap);
console.log(myObj); // {apple: 2, orange: 3}

3. Convert array to Map object

Convert array to Map object, which can be achieved by traversing the array . The syntax is as follows:

new Map(array);

Among them, array represents the array to be converted. For example:

var myArray = [["apple", 2], ["orange", 3]];
var myMap = new Map(myArray);
console.log(myMap); // Map {"apple" => 2, "orange" => 3}

4. The object is converted into a Map object

The object is converted into a Map object, which can be achieved by traversing the object. The syntax is as follows:

new Map(Object.entries(obj));

Among them, obj represents the object to be converted. For example:

var myObj = {apple: 2, orange: 3};
var myMap = new Map(Object.entries(myObj));
console.log(myMap); // Map {"apple" => 2, "orange" => 3}

3. Summary

This article introduces the use of Map objects in JQuery, as well as methods to realize conversion between Map objects, arrays, and objects.

Using Map objects can conveniently store key-value pairs, and conversion methods can help us use different data types in different scenarios. I hope this article can help developers better use JQuery for programming.

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