However, when the file size grows to 1GB, or even 2GB, then the page might crash in browser or not function correctly. The result will be stored on this.result after the 'load' event fires. Constructors. It exposes those 4 reading methods we can use to start a reading process: readAsText() readAsDataURL() readAsArrayBuffer() readAsBinaryString() and an abort() method to halt any reading operation. The FileReader object asynchronously reads the content of a file. In addition to Blob methods and properties, File objects also have name and lastModified properties, plus the internal ability to read from filesystem. Like the also asynchronous Ajax calls, the FileReader also has loading states that help to ascertain the progress of the read. Links. FileReader.readAsText() Starts reading the contents of the specified Blob, once finished, the result attribute contains the contents of the file as a text string. The FileReader API is really handy if you need to read a file using JavaScript. FileReader objects can read from a file or a blob, in one of three formats: String (readAsText). HTML5 FileReader API allows you to upload files or blob in the browser very easily.

JSFiddle or its authors are not responsible or liable for any loss or damage of any kind during the usage of provided code. For that reason, you can't just refer to the file contents after calling it. In this tutorial, I am going to share with you how you can use HTML5 FileReader API to upload images and text files from the client side in the web browser. Begins reading from blob as a string. Every byte is represented by an integer in the range [0..255]. FileReader is used to read the contents of a Blob or File. Specifications It is very easy to use FileReader.readAsText() to process a 300K log file. - FileReader.readAsText(Blob|File, opt_encoding) – The result property will contain the file/blob’s data as a text string. The FileReader API in HTML5 allows web browsers to access user files without uploading the files to the web servers. The readAsText() method used above is asynchronous. Use the optional encoding parameter can specify a different format. FileReader.readAsText( Blob , "文字セット" ) :Void. By default the string is decoded as ‘ UTF-8’. FileReader.readAsDataURL() Starts reading the contents of the specified Blob, once finished, the result attribute contains a data: URL representing the file's data. 第01引数 ... 解釈してテキスト文字列を得る） // -----file_reader. ... readAsText (blob : Blob, [encoding : String]) : undefined. FileReaderオブジェクトには、下記のようなメソッドがあり（非推奨のものは除く）、Blobオブジェクトを様々な形式で読み取ることができる readAsArrayBuffer() →ArrayBuffer; readAsDataURL() →DataURL; readAsText() →文字列; abort() →読み取り中断 There's a whole bunch of different methods available that allow you to get a file's content in various formats. Spec. We usually get File objects from user input, like or Drag’n’Drop events (ondragend). readAsText(file, encoding)readAsDataURL(file)readAsBinaryString(file)readAsArrayBuffer(file)Pass in a File or Blob … Bug tracker Roadmap (vote for features) About Docs Service status. answer 1 >> 解决方法.

To set File content into innerHtml you must first read the file.loadend event fires only when file is fully readed, and you can access its contect without errors:. new FileReader : FileReader.

It not only lightens the load of web server but also saves the time of uploading files. HTML5 FileReader API provides a convenient way to communicate with local files through the local device.