How to find whether an element in an array exists in jquery

In the process of developing with jQuery, we usually encounter a very common problem, that is, how to determine whether an element exists in an array. In this article, we'll explore a few different ways to accomplish this task.

Method 1: Use jQuery’s inArray() method

In jQuery, we can use the inArray() method to determine whether an element exists in an array. The inArray() method can receive two parameters. The first parameter is the element to be searched, and the second parameter is the array to be searched. This method returns the index value of the found element in the array, or -1 if it is not found.

The following is a simple example code that uses the inArray() method to find whether an element exists in an array:

var arr = ['apple', 'banana', 'orange', 'grape'];
var index = $.inArray('banana', arr);
if (index != -1) {
  console.log('元素存在于数组中，索引值为：' + index);
} else {
  console.log('元素不存在于数组中');
}

Code explanation:

First defines an array containing four fruits An array of names, and use the inArray() method to find whether the array contains the element "banana". If the index value returned by the inArray() method is not equal to -1, it means that the element exists in the array, and the index value of the element is output in the console. On the other hand, if the index value is equal to -1, then it means that the element does not exist in the array, and this information is output to the console.

Method 2: Use jQuery’s grep() method

Another jQuery method that can be used to determine whether an element exists in an array is the grep() method. Like the inArray() method, the grep() method also receives two parameters. The first parameter is the array to be searched, and the second parameter is the search condition. The grep() method returns a new array containing elements that meet the criteria, or an empty array if no elements are found.

The following is a simple example code that uses the grep() method to find whether an element exists in an array:

var arr = ['apple', 'banana', 'orange', 'grape'];
var result = $.grep(arr, function (n) {
  return n == 'banana';
});
if (result.length > 0) {
  console.log('元素存在于数组中');
} else {
  console.log('元素不存在于数组中');
}

Code explanation:

Use the grep() method to find an array Does it contain the element "banana"? If the length of the new array returned by the grep() method is greater than 0, it means that the element exists in the array and this information is output to the console. On the other hand, if the length of the new array is equal to 0, it means that the element does not exist in the array.

Method 3: Use the includes() method in ECMAScript 6

In the ECMAScript 6 specification, a new method includes() is provided to determine whether an element exists in an array . Using the includes() method, we can easily determine whether an element exists in an array.

The following is a simple example code that uses the includes() method to find whether an element exists in an array:

var arr = ['apple', 'banana', 'orange', 'grape'];
if (arr.includes('banana')) {
  console.log('元素存在于数组中');
} else {
  console.log('元素不存在于数组中');
}

Code explanation:

Use the includes() method to determine " Whether the element "banana" exists in the array. If the element exists in the array, print this information to the console. On the contrary, if the element does not exist in the array, the non-existent information will be output to the console.

Summary

This article introduces several different methods to determine whether an element exists in an array, including jQuery's inArray() and grep() methods, as well as ECMAScript 6's includes() method. These methods are very convenient and practical. Which method you choose depends entirely on your personal habits and project needs.

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