Use a simple jQuery code snippet to find the index of an array item with a known item value. This is a bit similar to the Array.FindIndex method of .NET, but uses the inArray function.

// 語法
jQuery.inArray(value, array)

// 示例
jQuery.inArray("Sam", array)

FAQs for jQuery Index Find and Array Items

How does the findIndex() method in JavaScript work?

The findIndex() method in JavaScript is a built-in function that finds the first element in an array that satisfies the test function. It executes a function once on each index in the array until it finds an index that returns the true value. If such an element is found, findIndex() will immediately return the index of the element. Otherwise, it returns -1.

What is the difference between findIndex() and indexOf() in JavaScript?

findIndex() and indexOf() are both used to find the index of elements in an array. However, there are some key differences between them. The indexOf() method returns the first index where the given element can be found in the array, and -1 if it does not exist. It uses strict equality (the same method as === or the three equality operator) to compare elements. On the other hand, findIndex() executes a callback function on each element in the array until the callback function returns the true value, and then it returns the index of that element. If no such element is found, it returns -1.

Can I use findIndex() in jQuery?

Yes, you can use findIndex() in jQuery. However, it should be noted that jQuery does not have a built-in findIndex() method. Instead, you can use the $.inArray() method, which is similar to the indexOf() method of JavaScript. If you want to use findIndex() in jQuery, you need to convert your jQuery object to a JavaScript array first.

How to use findIndex() in an array of objects?

You can use findIndex() in an object array by providing a callback function that checks for specific conditions. The callback function should return true for the object you are looking for and false for all other objects. Here is an example:

let array = [{id: 1, name: 'John'}, {id: 2, name: 'Jane'}, {id: 3, name: 'Joe'}];
let index = array.findIndex(obj => obj.id === 2);
console.log(index); // 輸出：1

What happens if multiple elements satisfy the test function in findIndex()?

If multiple elements satisfy the test function in findIndex(), the method returns the index of the first element that satisfies the function. It does not continue to check for the remaining elements in the array.

Can I use findIndex() on strings?

No, you cannot use findIndex() on strings. The findIndex() method is only applicable to array objects. If you want to find indexes of characters or substrings in a string, you can use the indexOf() or lastIndexOf() method.

findIndex() Is it supported in all browsers?

findIndex() method is not supported in Internet Explorer. However, it is supported in all modern browsers, including Chrome, Firefox, Safari, and Edge.

Can I use findIndex() in a multidimensional array?

Yes, you can use findIndex() in multidimensional arrays. However, you need to provide a callback function that can handle nested arrays. The callback function needs to iterate over the subarray and check the conditions you are looking for.

How to use findIndex() to find the last element that meets the criteria?

findIndex() method returns only the index of the first element that satisfies the provided test function. If you want to find the last element that meets the condition, you need to invert the array using the reverse() method and then call findIndex().

Can I use findIndex() in typed arrays?

Yes, you can use findIndex() in typed arrays. Typed arrays are objects similar to JavaScript arrays and provide a way to access raw binary data. Just like a regular array, you can use findIndex() to find the index of the first element in the typed array that satisfies the provided test function.

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