Create a new file called text. The second parameter is used to specify the encoding of the file. First we need to get references to the important elements within our HTML.
You can use this data URL for things like setting the src property for an image. The [AsyncResult] object is passed in as the single parameter to the callback method that you specify in the Ewa.
This method has two parameters.
EwaControl] object is included in the [AsyncResult] object. We then create another variable called textType that holds a regular expression that we will use later to test that the selected file is indeed a text file.
Finally we call the readAsText method, passing in the file variable that we created earlier. This time we want an image file so the regular expression is: This will be fired whenever the user selects a file.
We start by creating a new instance of FileReader and then setting up an event listener for the onload event.
We then add img to the fileDisplayArea using appendChild. This second parameter is optional. EwaControl] object through the [AsyncResult] object. An ArrayBuffer is a fixed-length binary data buffer.
In this blog post you are going to learn how to use the FileReader API to read the contents of a file from your local hard drive. This can come in handy when reading large files. The API will work in the latest versions of all the major desktop browsers. Once we have determined that the file type is correct we create a new instance of FileReader.
As this is an asynchronous method we need to setup an event listener for when the file has finished loading. These methods are all asynchronous which means that your program will not stall whilst a file is being read.
This is basically a base64 encoded string of the file data. The first application will handle reading and then displaying the contents of a text file. To get started we first need to setup the HTML for our demo. Click here to try a free trial on Treehouse.
We first fetch the first file from our input by examining the fileInputs files property and store this in a variable called file. Then you include code in the page that interacts with the embedded workbook.
We will look at how to do this later in the images demo. The following code example shows how you get a reference to the [Ewa. Do you want to learn more about HTML5? EwaControl] object by using the method, Ewa. This is particularly useful when dealing with large files.
Within this event listener we add some code that will update the innerText property of fileDisplayArea using the result property from our FileReader. The first parameter is for the File or Blob object that is to be read. When the callback is invoked, a reference to the [Ewa.