In internet improvement, it is usually essential to examine the file extension of a file to find out its sort. This may be achieved in JavaScript utilizing the `cut up()` methodology. For instance, the next code checks if a file has a `.jpg` extension:
const fileName = "picture.jpg"; const extension = fileName.cut up('.').pop(); if (extension === "jpg") { // The file is a JPEG picture. } Checking the file extension may be helpful for quite a lot of functions. For instance, you should use it to: