jquery .inarray usage

jQuery's .inArray() method can be used to find a specific element in an array and return its index value (if found). Its usage is as follows:

$.inArray(value, array [, fromIndex])

Parameter description:

• value: The value to be found
• array: To Array to search
• fromIndex (optional): Start searching from the specified position

Return value:

• If found If an element is found, its index value in the array (starting from 0) is returned, otherwise -1 is returned.

For example, let's say we have an array arr:

var arr = [2, 4, 6, 8];

If we want to see if the number 4 is in this array, we can use .inArray() method, as follows:

if ($.inArray(4, arr) !== -1) {
  console.log('4在数组中');
} else {
  console.log('4不在数组中');
}

In this example, we pass the value to be found (4) and the array to be found (arr) as parameters to .inArray()Method. If 4 is in the array, the .inArray() method will return its index value (1) and we will get the message "4 in array" printed out. Otherwise, -1 will be returned and we will get the message "4 not in array" printed out.

We can also specify an index value to start searching. For example:

var arr = [2, 4, 6, 8];
var startIndex = 2;

if ($.inArray(6, arr, startIndex) !== -1) {
  console.log('6在数组中');
} else {
  console.log('6不在数组中');
}

In this example, we will find the elements in the array starting from the index value 2, i.e. starting from the number 6. If 6 is in the array, we will get the message "6 is in the array" printed out. Otherwise, -1 will be returned and we will get the message "6 is not in the array" printed out.

In summary, the .inArray() method can help us find a specific element in an array and return its index value. We can also specify where to start the search. This method is very practical, especially when dealing with arrays in Javascript.

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