The FileReader instance has a readAsText method that we can use to read a file as text: const reader = new FileReader(); reader.readAsText(file); Since the FileReader API is asynchronous, it exposes several events that we can use to get its state. There are 6 main events attached to FileReader: loadstart: Fires when we start loading a file. var reader = new FileReader(); What are the Methods to work on FileReader? FileReader Lifecycle. Creating a FileReader … How to select files, ... For example, an image editing app should only accept images, not text files. readAsText() It is used to read the contents of the specified Blob or File. progress: Fires when the blob is read in memory.
var file = evt.target.files; var reader = new FileReader(); reader.readAsText(file); 今度はファイルが選択された場合の処理を見ていきましょう。最初はtarget.filesで選択されたファイルを取得し、 変数fileに格納しています。 次にFileReaderを作成し、変数readerに格納します。 reading and writing a single character or an array of characters at once.
It is working in Chrome, Opera and Firefox. The readAsText() method is used to read the contents of the specified Blob or File. The FileReader type. The result attribute contains a URL representing the file’s data. This function returns the file contents as plain text. FileReader is an object with the sole purpose of reading data from Blob (and hence File too) objects. The FileReader object lets web applications asynchronously read the contents of files (or raw data buffers) stored on the user's computer, using File or Blob objects to specify the file or data to read.. The API is intentionally designed to be similar to XMLHttpRequest since both are loading data from an external (outside of the browser) resource.