In JavaScript, there are multiple ways to read a file, but one common way is to use the FileReader API. Here's an example of how to read a file in JavaScript - ECMAScript 2021:
// create a new FileReader object
const fileReader = new FileReader();
// use the readAsText method to read the contents of the file
fileReader.readAsText(file);
// handle the onload event to get the contents of the file
fileReader.onload = function() {
const fileContent = fileReader.result;
console.log(fileContent);
};
In the above code, file is the file object that you want to read. The readAsText method is used to read the contents of the file as a string. Once the contents of the file have been read, they are accessible through the result property of the FileReader object. In this example, we log the contents of the file to the console.
Additionally, it's important to note that to actually select the file, you will need to use an HTML element with a change event listener to pass the selected file to the JavaScript function:
In this example, we listen for the change event on the fileInput element and use the files property of the event target to get the selected file. We then pass the selected file to the FileReader API to read its contents.