Convert jquery array to key-value pair

In front-end development, the processing of arrays and objects is often involved. When we need to convert an array into key-value pairs, we can use the $.map() and $.each() methods in jQuery. The following is a detailed introduction to the use of these two methods.

1. $.map() method

$.map() method can convert one array to another array, and during this conversion process, we can perform operation and returns a new value. Its basic syntax is as follows:

jQuery.map( array, callback [, thisArg ] )

Among them, array represents the array to be processed, callback represents a callback function used to operate each element and return a new value, and thisArg represents the optional context object.

For the scenario of converting into key-value pairs, we can use the $.map() method to process the original array and convert each element in it into a key-value pair object.

For example, we have an array arr, which contains some string elements. Now we want to convert it into a key-value pair, in which all elements are keys and their values ​​​​are true, then we can Write like this:

var arr = ["apple", "pear", "banana", "orange"];
var kvObj = $.map(arr, function(item, index) {
    var obj = {};
    obj[item] = true;
    return obj;
});
console.log(kvObj); // [{ apple: true }, { pear: true }, { banana: true }, { orange: true }]

In the above code, we define a callback function that receives two parameters item and index. This function converts each element into an object where the element is the key and the value is true, and returns the object. The final result returned is an array of objects, each object is a key-value pair.

2. $.each() method

Unlike the $.map() method, the $.each() method can traverse an array or object and execute a callback on each element function. The parameters of the callback function include the key and value of the element.

Its basic syntax is as follows:

jQuery.each( collection, callback(indexInArray, valueOfElement) )

Among them, collection represents the object or array to be traversed, and callback represents the callback function that processes each element.

We can convert an array into key-value pairs, or we can do it through the $.each() method.

For example, we have an array arr, which contains some string elements. Now we want to convert it into a key-value pair, in which all elements are keys and their values ​​are the corresponding elements in the array. The index position in , then you can write it like this:

var arr = ["apple", "pear", "banana", "orange"];
var kvObj = {};
$.each(arr, function(index, item) {
    kvObj[item] = index;
});
console.log(kvObj); // { apple: 0, pear: 1, banana: 2, orange: 3 }

In the above code, we define a callback function that receives two parameters index and item. Each time an element is traversed, the element is used as the key and its index position is used as the value, stored in an object. The final result returned is a key-value pair object.

Summary:

The above are two methods of converting jQuery arrays into key-value pairs. Suitable for different scenarios, you can freely choose which method to use. When dealing with arrays and objects, we can reasonably use the $.map() and $.each() methods according to actual needs to improve the efficiency and readability of the code.

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