Develop Reference

How can I delete blob files in JavaScript?

I am creating an image viewer using XMLHttpRequest. It includes this function:
public view_image(_tImagen: iConfigImagen){
var img_view = this.prop_div_vizualizador;
var _window: any = window;
var xhr = new XMLHttpRequest();
xhr.open("GET", _tImagen.url, true);
xhr.responseType = "blob";
xhr.onload = function () {
var urlCreator = _window.URL = _window.URL || _window.webkitURL;
var imageUrl = urlCreator.createObjectURL(this.response);
_tImagen.urlBlob = imageUrl;
img_view.style("background-image", "url(" + _tImagen.urlBlob + ")");
}
}
It works fine, but I am trying to delete the blob files that it generates somehow. I tried URL.revokeObjectURL(url), but that only deletes the url and not the file. How can I delete the files? Is there any way to remove them?
Thanks in advance.

The XMLHttpRequest allows you to make an HTTP request and receive a response, but it does not give you access to the file system. You cannot delete files without access to them.

Read the excel file from the specific location

I don't want to use this way(link)
because I don't want to open new window for file selection.
I just want to load & read excel file when I click some button.
But this is not work.. help me to load the excel file.
MYCODE:
const FILE_NAME = "C:/Users/A/project_list.xlsx";
function LoadSpread(json) {
jsonData = json;
workbook.fromJSON(json);
workbook.setActiveSheet("Revenues (Sales)");
}
function excelExport(fileName) {
console.log(fileName);
var excelUrl = fileName;
var oReq = new XMLHttpRequest();
oReq.open("get", excelUrl, true);
oReq.responseType = "blob";
oReq.onload = function() {
var blob = oReq.response;
excelIO.open(blob, LoadSpread, function(message) {
console.log(message);
});
};
oReq.send(null);
}
function chkPrtNum(event) {
var fileName = FILE_NAME;
excelExport(fileName);
}

Try creating a small server for the same, you will easily get your job done. – Raghu Chahar Jan 28 at 9:50
This was very helpful

Getting blob gives 404 error

could someone prompt me - how to save "blob in memory" to a file using Java Script?
e.g. I have in the page next blob-image:
<img src="blob:https%3A//drive.google.com/851b979c-92e9-4ef2-9152-8935f7793630" class="g-img">
and I need to save this blob to a file (png/jpg).
The next code just gives:
GET blob:https%3A//drive.google.com/851b979c-92e9-4ef2-9152-8935f7793630 404 (Not Found)
so it seems, usual way to get the blobs doesn't work here.
Is there any workaround to save this blob-images from browser memory to a file, or, saying more exactly - to get them as a real blob using only "src" tag value?
Thank you.
var srcEl = evt.srcElement;
var CurI = document.getElementsByClassName('g-img');
[].forEach.call(CurI, function (el) {
var xhr = new XMLHttpRequest();
xhr.open('GET', el.src, true);
xhr.responseType = 'arraybuffer'; // xhr.responseType = 'blob';
xhr.onload = function(e) {
if (this.status == 200) {
var myBlob = this.response;
var reader = new window.FileReader();
reader.readAsDataURL(myBlob);
console.log(myBlob);
}
};
xhr.send();
console.log(el.src);
// saveAs(myBlob, 'my2image.png');
}
p.s. to use mediarecorder?

Using Javascript to Create a XML Document from a HTML Form

I'm having a lot of difficulty with this project.
My aim is to write the results of a HTML form to an XML Document using Javascript.I have absolutely no idea how to do it.
Reason why I'm coming here is that I want to be sure that I'm on the right track. So far, I'm writing only one line "\n" just to test things out.
Here is my current JavaScript
var xhr = false;
if (window.XMLHttpRequest)
{
xhr = new XMLHttpRequest();
}
else if (window.ActiveXObject)
{
xhr = new ActiveXObject("Microsoft.XMLHTTP");
}
function StoreRegXml()
{
xhr.open("GET", "php.php?" + Number(new Date), true);
xhr.onreadystatechange = getData;
xhr.send(null);
}
function getData()
{
if ((xhr.readyState == 4) && (xhr.status == 200))
{
var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
var fso = new ActiveXObject("Scripting.FileSystemObject");
var filename = "customer.xml";
var file = fso.CreateTextFile(filename, true);
file.WriteLine('<?xml version="1.0" encoding="utf-8"?>\n');
file.Close();
}
}
Am I on the right track?
Edit: I'm adding alerts('test1'); to see where the code is going wrong and it stops at
var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
Any ideas?

Inside the browser to create and populate an XML DOM document you can use the W3C DOM APIs with e.g.
var xmlDoc = document.implementation.createDocument(null, 'root', null);
var foo = xmlDoc.createElement('foo');
foo.textContent = 'bar';
xmlDoc.documentElement.appendChild(foo);
console.log(xmlDoc);
This creates an in memory XML DOM document, not an XML file. You can then for instance send the xmlDoc with XMLHttpRequest to the server.

XMLHttpRequest on load in saveback to calling object

I'm trying to load in many json files for a HTML5 game that will serve as sprite sheets. Previously I've did this synchronously but my new goal is to do this asynchronously.
I have run into a problem though where I'm trying to saving back to the calling object. This is so the information loaded can be used later and so a flag (loaded) can be set so the system knows when a resource has been loaded. Below is my XMLHttpRequest code. I have substituted "spritesheet" for what ever the call should be to save back to the parent.
function SpriteSheet(filename)
{
var tmpFileName = "json/" + filename;
this.loaded = false;
var xhr = new XMLHttpRequest();
xhr.open("GET",tmpFileName,true);
xhr.onload = function(event){
var parsed = JSON.parse(this.responseText);
"spritesheet".img=new Image();
"spritesheet".img.src = "imgs/" + parsed["imgLoc"];
"spritesheet".animations = parsed["animations"];
"spritesheet".sprites = parsed["sprites"];
"spritesheet".loaded = true;
};
xhr.send();
}
Can somebody inform me how I can save back to the the parent or if this is completely the wrong approach can they point me in the direction of a solution.

I found that by creating a var in the 'class' that is a reference to the object and using it in the onload function works, for example:
function SpriteSheet(filename)
{
var tmpFileName = "json/" + filename;
this.loaded = false;
var caller = this;
var xhr = new XMLHttpRequest();
xhr.open("GET",tmpFileName,true);
xhr.onload = function(event){
var parsed = JSON.parse(this.responseText);
caller.img=new Image();
caller.img.src = "imgs/" + parsed["imgLoc"];
caller.animations = parsed["animations"];
caller.sprites = parsed["sprites"];
caller.loaded = true;
};
xhr.send();
}