findIndex() Method in JavaScript

The method in JavaScript is used to find the index of the first element that matches a specific condition.
It is similar to the method, but instead of returning the element itself, it returns the index of that element.
If no element satisfies the condition, returns .

How Works:

The method takes a callback function that is executed for each element.
If the condition is satisfied, it returns the index of the first matching element.
If no match is found, it returns .

Example:

We have a array containing some blog posts with , , and :

1const blogs = [
2    { id: 1, title: 'Title-1', description: 'Description-1' },
3    { id: 2, title: 'Title-2', description: 'Description-2' },
4    { id: 3, title: 'Title-3', description: 'Description-3' }
5];

Using findIndex() to Locate a Blog by ID:

We want to find the blog with using .

1function foundBlog(blogId) {
2    return blogs.findIndex(blog => blog.id === blogId);
3}

Here:

The method iterates over the array to locate the first blog with the matching (in this case, ).
The index of the blog is returned by the function.

Checking the Index:

We store the result of the function in :

1const foundIndex = foundBlog(2);

Displaying the Blog:

We check if the index is not , which means the blog was found. If found, we print the blog details, otherwise, we display "Blog not found":

1if (foundIndex !== -1) {
2    document.write(`
3        Title: ${blogs[foundIndex].title}, <br>
4        Description: ${blogs[foundIndex].description}
5    `);
6} else {
7    document.write("Blog not found!");
8}

Output:

If the blog is found, the output will be:

1Title: Title-2, 
2Description: Description-2

If no matching blog is found:

1Blog not found!

Summary:

The method is useful for finding the index of an element based on a condition.
It returns if no matching element is found.
The method is ideal when you need the position of an element, rather than the element itself.

findIndex() Method in JavaScript

findIndex() Method in JavaScript

How Works:

Example:

Using findIndex() to Locate a Blog by ID:

Checking the Index:

Displaying the Blog:

Output:

Summary:

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