Databases
StackOverflow2013
Postsdbo
POUsing the HTML5 FileWriter truncate() method?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POUsing the HTML5 FileWriter truncate() method?
    primarykey
    data
    text
    <p>I'm experimenting with the HTML5 File API, and I'm needing to use a method which I don't know enough about (simply because it's hardly documented anywhere).</p> <p>I'm talking about the FileWriter truncate() method, and I know it does what I need to do. Basically, rather than appending text to some file data or using seek() to overwrite a certain portion, I want to overwrite all of the data with something else (e.g. from "somedata" to "").</p> <p>Here's a snippet of the FileWriter setup from HTML5Rocks, with truncate() added in.</p> <pre><code>function onInitFs(fs) { fs.root.getFile('log.txt', {create: false}, function(fileEntry) { // Create a FileWriter object for our FileEntry (log.txt). fileEntry.createWriter(function(fileWriter) { fileWriter.seek(fileWriter.length); // Start write position at EOF. fileWriter.truncate(1); // Create a new Blob and write it to log.txt. var bb = new BlobBuilder(); // Note: window.WebKitBlobBuilder in Chrome 12. bb.append('Hello World'); fileWriter.write(bb.getBlob('text/plain')); }, errorHandler); }, errorHandler); } window.requestFileSystem(window.PERSISTENT, 1024*1024, onInitFs, errorHandler); </code></pre> <p>When it gets to calling writer.truncate(), calling writer.write() throws a File Exception error. I believe this is because the readyState is set to WRITING. Unfortunately, I don't know how to get around that.</p> <p>I've already tried looking through the <a href="http://www.html5rocks.com/en/tutorials/file/filesystem/#toc-file-writing" rel="nofollow noreferrer">HTML5Rocks section</a> on this, but it doesn't tell me anything about a truncate() method (although I know it exists from what the Webkit JS Console tells me).</p> <p>Long story short, how I can I use the truncate() method correctly without getting an error?</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. UScaleb531
    1. UScaleb531
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POUsing the HTML5 FileWriter truncate() method?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POUsing the HTML5 FileWriter truncate() method?
      1. USsw.
      1. VTFavorite
    3. VO
      singulars
      1. POUsing the HTML5 FileWriter truncate() method?
      1. This table or related slice is empty.
      1. VTUpMod
    1. CO[W3C truncate spec](http://www.w3.org/TR/file-writer-api/#widl-FileWriter-truncate) enjoy.
      singulars
      1. POUsing the HTML5 FileWriter truncate() method?
      1. USRaynos
    2. COWhy truncate(1)? Why not truncate(0) to get a zero-sized file?
      singulars
      1. POUsing the HTML5 FileWriter truncate() method?
      1. UShuyz
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload