Read files javascript examples

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Are you looking for the ways to access the file system using JavaScript? If your JavaScript code could access local files of the visitor to your site, it would be a huge security problem. That's why no browsers would allow it JavaScript is a simple yet very powerful scripting language. As mentioned in the chapter Blob , FileReader can read not just files, but any blobs. They do not affect the page. In addition to Blob methods and properties, File objects also have name and lastModified properties, plus the internal ability to read from filesystem.

Just as we did with blobs, we can create a short url with URL. This way the file can be downloaded or shown up as an image, as a part of canvas etc.

We want to make this open-source project available for people all around the world. Syntax: readFile Path, Options, Callback Parameters: This method accepts three parameters as mentioned above and described below:.

Skip to content. Change Language. Related Articles. Table of Contents. Improve Article. Save Article. Like Article. When the drop event is fired, it will include a File object for the directory, but will be unable to access any of the files within the directory.

The File object contains a number of metadata properties about the file. Most browsers provide the file name, the size of the file, and the MIME type, though depending on the platform, different browsers may provide different, or additional information. You can see this in action in the input-type-file Glitch demo. To read a file, use FileReader , which enables you to read the content of a File object into memory. The example above reads a File provided by the user, then converts it to a data URL, and uses that data URL to display the image in an img element.

Check out the read-image-file Glitch to see how to verify that the user has selected an image file. When reading large files, it may be helpful to provide some UX to indicate how far the read has progressed. For that, use the progress event provided by FileReader. The progress event provides two properties, loaded , the amount read, and total , the total amount to read.