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Copy QR CODE image to clipboard and paste to share. I use Vuejs? [duplicate]

Seemingly, you can't (yet) programmatically copy an image to the clipboard from a JavaScript web app?
I have tried to copy a text in clipboard , and it's worked.
Now I would like to copy an image and after I press ctrl+v to paste into Word or Excel or Paint.
$(function() {
$("#btnSave").click(function() {
html2canvas($("#container1"), {
onrendered: function(canvas) {
theCanvas = canvas;
document.body.appendChild(canvas);
Canvas2Image.saveAsPNG(canvas);
$("#img-out").append(canvas);
}
});
});
});

For those still looking, the ClipboardAPI now works with png images.
try {
navigator.clipboard.write([
new ClipboardItem({
'image/png': pngImageBlob
})
]);
} catch (error) {
console.error(error);
}

This worked across all browsers (as of 2016). I have uploaded on GitHub as well: https://github.com/owaisafaq/copier-js
//Cross-browser function to select content
function SelectText(element) {
var doc = document;
if (doc.body.createTextRange) {
var range = document.body.createTextRange();
range.moveToElementText(element);
range.select();
} else if (window.getSelection) {
var selection = window.getSelection();
var range = document.createRange();
range.selectNodeContents(element);
selection.removeAllRanges();
selection.addRange(range);
}
}
$(".copyable").click(function(e) {
//Make the container Div contenteditable
$(this).attr("contenteditable", true);
//Select the image
SelectText($(this).get(0));
//Execute copy Command
//Note: This will ONLY work directly inside a click listenner
document.execCommand('copy');
//Unselect the content
window.getSelection().removeAllRanges();
//Make the container Div uneditable again
$(this).removeAttr("contenteditable");
//Success!!
alert("image copied!");
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="copyable">
<img src="https://via.placeholder.com/80" alt="Copy Image to Clipboard via Javascript." />
</div>
<div class="copyable">
<img src="https://via.placeholder.com/80" alt="Copy Image to Clipboard via Javascript." />
</div>

So, i created the perfect solution with 1 liner-kinda solution to convert something with html2canvas to a canvas and then produce the image of it and then save it to clipboard as png. For example,
HTML:
<div id="copyToImage">Hello World!</div>
JavaScript:
$("#copyToImage").click(function() {
html2canvas(document.querySelector("#copyToImage")).then(canvas => canvas.toBlob(blob => navigator.clipboard.write([new ClipboardItem({'image/png': blob})])));
});

You are right. There is no support to copy image data into clipboard in chrome yet. https://bugs.chromium.org/p/chromium/issues/detail?id=150835.
Looks like it has been open for about 4 years now.
There is a clipboard API spec that is coming up though
https://w3c.github.io/clipboard-apis/

Well, this is my first post in here with an answer i guess :)
Actually i'm currently using cefsharp web browser component one of my project, cefsharp run on chrome based browser and i want to copy img element one of webpage
With cefsharp you can manipulate browser only javascript, so i think we can handle it with using canvas element.
/*
'cause of lorempixel timeout, i used img onload function.
*/
function copyImage() {
var imgCap = document.getElementById('imgCap');
var imgCanvas = document.createElement('canvas');
imgCanvas.id = 'imgCanvas';
imgCanvas.height = 40;
imgCanvas.width = 120;
document.body.appendChild(imgCanvas);
var originalContext = imgCanvas.getContext('2d');
originalContext.drawImage(imgCap, 0, 0);
//return imgCanvas.toDataURL();
}
//document.onload = copyImage();
<img id="imgCap" src="http://lorempixel.com/120/40" onload="copyImage();"/>
with return imgCanvas.toDataURL(); you can get base64 encoded value and use wherever you want.
this is my cefsharp code, it's working.
string copyImageOtClipboardScript = "(function(){ try{var imgCap = document.getElementById('imgCap'); var imgCanvas = document.createElement('canvas'); imgCanvas.id = 'imgCanvas'; imgCanvas.height = 40; imgCanvas.width = 120; document.body.appendChild(imgCanvas); var originalContext = imgCanvas.getContext('2d'); originalContext.drawImage(imgCap, 0, 0); return imgCanvas.toDataURL(); }catch(e){ alert(e); } })();";
var task = chromeBrowser.EvaluateScriptAsync(copyImageOtClipboardScript).ContinueWith(x =>
{
var resp = x.Result;
if (resp.Success)
{
this.Invoke((MethodInvoker)delegate
{
Bitmap bmp = null;
string captchaResult = "", captchaBase64;
var bytes = Convert.FromBase64String(resp.Result.ToString().Replace("data:image/png;base64,", ""));
using (var imageFile = new FileStream("temp_captcha.png", FileMode.Create))
{
imageFile.Write(bytes, 0, bytes.Length);
imageFile.Flush();
}
});
}
});

This can be achieved by using the Clipboard API, which does require that your server is secured. The basic idea is to convert your image to a blob before writing it to the clipboard as an image.
const img = document.querySelector("#b64-img");
const copyBtn = document.querySelector("#copy");
copyBtn.onclick = e => {
const canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
canvas.getContext("2d").drawImage(img, 0, 0, img.width, img.height);
canvas.toBlob((blob) => {
navigator.clipboard.write([
new ClipboardItem({ "image/png": blob })
]);
}, "image/png");
};
<img id="b64-img" src="data:image/png;base64,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">
<br>
<button id="copy">Copy Above Image</button>
This will allow you to paste your image to Photoshop and other image-applications.

Check out this guide to copying and pasting with JavaScript: https://www.lucidchart.com/techblog/2014/12/02/definitive-guide-copying-pasting-javascript/
According to this, Chrome, Safari, and Firefox all support copying images along with plain text, while IE only allows copying text. The page linked above describes how this service uses an extension to add this functionality to a context menu, but it appears that several browsers support programmatic copying of images.

const copyImageToClipboard = async () => {
try {
await navigator.clipboard.write([
new ClipboardItem({
'image/png': await fetch(img).then((r) => r.blob()),
}),
]);
} catch (error) {
console.error(error);
}
};
You might run into CORS errors testing on localhost. But you can install a CORS extension to get rid of that issue :)

var image = new Image();
image.src = url;
copyImageToClipboard(image.src);
install it from https://www.npmjs.com/package/copy-image-clipboard

Here is the best answer i found for you, very simple and its working 100% exactly what you need.
await navigator.clipboard.writeText(code);
Check out this link: enter link description here

You cannot copy to clip board with Javascript for security reasons, a work around can be found in a discussion here. Involves flash.Click button copy to clipboard using jQuery

Base64 image not opening up when converted from Image URL

I am converting an image to Base64 from Image URL using canvas. The approach I am taking is similar to below 2 links but the converted Base64 string is not opening up the image when viewed in Chrome Tab.
Links
CONVERT Image url to Base64
(1st answer with 81 thumbs up).
https://jsfiddle.net/3qshvc54/
I tried consoling the img, canvas, ctx in fiddle and my code. The console output is the same. Please see below screenshots.
If I do it by fiddle the converted Base64 URL opens up fine in a new tab, but the one generated from my code does not display an image when opened up in a new tab.
I am using same Image URL in my code and Fiddle
Console screenshot when running from my code
Console screenshot when running from Fiddle
The Base64 generated from my code:
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEQAAABDCAYAAAAlFqMKAAAApklEQVR4Xu3VsQ0AIAwEMbL/0tShQLrejHB6kzneKjB67AKCPIsQRJD/J2EhFmIh6ZAigwwyyKQCyCCTBuPKIIMMMqkAMsikwbgyyCCDTCqADDJpMK4MMsggkwogg0wajCuDDDLIpALIIJMG48oggwwyqQAyyKTBuDLIIINMKoAMMmkwrgwyyCCTCiCDTBqMK4MMMsikAsggkwbjyiCDDDKpADL/XBfFQABED54eAwAAAABJRU5ErkJggg==
I tried validating the same online it shows that the Base64 string is valid:
When I try to decode the same:
It seems that the result of decoding is a binary data (MIME type detected as “image/png”) and because of this the data from “Text” may be damaged during the output.
My code:
<div className='image-root'>
<img id={`imageBlock-${props.photoBoxID}`} className="multi-image-photo" src={props.imgUrl} alt="photo"></img>
</div>
getBase64Image = (img) => {
img.crossOrigin = 'Anonymous';
var canvas = document.createElement("CANVAS");
canvas.width = img.width;
canvas.height = img.height;
console.log('img', img);
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
console.log('canvas', canvas);
console.log('ctx', ctx);
var dataURL = canvas.toDataURL();
console.log('dataURL', dataURL);
}
componentDidUpdate(prevProps, prevState){
if(this.props.isUploaded && (prevProps.isUploaded !== this.props.isUploaded)){
let imageRef = document.getElementById(`imageBlock-${this.props.photoBoxID}`);
imageRef.onload = this.getBase64Image(imageRef);
}
}
Can you suggest why the Base64 string generated is not opening up fine if converted from my code, though it opens up from Fiddle? Is it corrupted?

onload is an event you need function there and in that function you need to update src.
componentDidUpdate(prevProps, prevState){
if(this.props.isUploaded && (prevProps.isUploaded !== this.props.isUploaded)){
let imageRef = document.getElementById(`imageBlock-${this.props.photoBoxID}`);
imageRef.onload = () => {
delete imageRef.onload;
imageRef.src = this.getBase64Image(imageRef);
};
}
}
but better is to add base64 image to state and don't use getElementById directly in React applications.
EDIT:
for infinite loop I would create 2 images, if you need to render image on canvas you usually render outside of DOM:
componentDidUpdate(prevProps, prevState){
if(this.props.isUploaded && (prevProps.isUploaded !== this.props.isUploaded)){
let imageRef = document.getElementById(`imageBlock-${this.props.photoBoxID}`);
var srcImg = new Image();
srcImg.onload = () => {
imageRef.src = this.getBase64Image(srcImg);
};
srcImg.src = prevProps.imgUrl;
}
}
and remove the props from JSX template you will not need it.
And side note: if you have big image it's better to create object URL from blob, because there is limit of data that can be put into URL (for smaller images it should not matter):
function asObjectUrl(canvas) {
return new Promise(function(resolve) {
canvas.toBlob(function(blob) {
resolve(URL.createObjectURL(blob));
});
});
}
The object url need to be removed when not needed to not create memory leaks (use URL.revokeObjectURL)

change your img's src attribute adding src="data:image/jpeg;base64 tag with the encoded string like below:
<img id={`imageBlock-${props.photoBoxID}`} className="multi-image-photo" src="data:image/jpeg;base64, ${props.imgUrl}" alt="photo"></img>
This should work.
N.B.: Please check your imageString variable carefully, I might have used the wrong one, not sure.

How to download the screenshot automatically by using html2Canvas

I have a canvas which shows a graph and I'm trying to take a screenshot of the canvas using html2canvas() with the code below :
<div class="chartContainer" id="chart1"></div>
<div id="displayCanvas" style="display:none;" class="stx-dialog"></div>
html2canvas($('#chart1'),{onrendered:function(canvas1)
{$('#displayCanvas').append(canvas1)}});
Here when the chart container is loaded the it uses the div with the id "displayCanvas" and appends the screenshot of the canvas.
How can I download the screenshot of the canvas which is displayed?
I have already tried using something like below to download the image:
var link = document.createElement('a');
link.download = stx.chart.symbol+".png";
link.href = stx.chart.canvas.toDataURL("png");
link.click();
but it only downloads the data on the canvas as an image without the background (it does not download the screenshot but only the data) which when opened after downloading shows a black screen with data in it. Can anyone help me on how to download the image directly of the screenshot taken from the html2Canvas()?

TRY THIS:
In the HTML:
Give the element that you want to screenshot, an ID of "capture".
Give the button/element that you would need to click to take the screenshot, an ID of "btn".
Load the html2canvas.min.js file.
In the Javascript:
Create the capture() function.
Bind the capture() function to whatever event you are using—in this case it's on the btn click event.
DONE! Watch the magic happen when you click on the btn.
HTML:
<h1 id="capture">Hellooooo</h1>
<button id="btn">Capture</button>
<script src="https://html2canvas.hertzen.com/dist/html2canvas.min.js"></script>
Javascript:
function capture() {
const captureElement = document.querySelector('#capture') // Select the element you want to capture. Select the <body> element to capture full page.
html2canvas(captureElement)
.then(canvas => {
canvas.style.display = 'none'
document.body.appendChild(canvas)
return canvas
})
.then(canvas => {
const image = canvas.toDataURL('image/png').replace('image/png', 'image/octet-stream')
const a = document.createElement('a')
a.setAttribute('download', 'my-image.png')
a.setAttribute('href', image)
a.click()
canvas.remove()
})
}
const btn = document.querySelector('#btn')
btn.addEventListener('click', capture)
Here's the JSFiddle
💡 QUICK TIP: If you want to capture the whole document/webpage, then just add the "capture" ID to the <body> tag.

If there is black background at image your chart must be visible on screen. Because html2canvas like a taking screenshot. If you want converting data
to canvas, you must be sure data is appear in screen.

In case someone is using React, here is some code you can copy:
async function download() {
const canvas = await html2canvas(document.querySelector("#screenshot"));
canvas.style.display = "none";
document.body.appendChild(canvas);
const image = canvas.toDataURL("image/png").replace("image/png", "image/octet-stream");
const a = document.createElement("a");
a.setAttribute("download", `info.png`);
a.setAttribute("href", image);
a.click();
}
<a href="#" onClick={() => download()}>Download</a>

This worked for me:
HTML
<div id="canvasDiv">
<canvas id="canvas" height="100" width="100">
Your browser does not support the HTML canvas tag.
</canvas>
</div>
<button onclick="screenShot()" type="button">Take a screenshot</button>
Javascript
function screenShot(){
html2canvas(document.querySelector("#canvasDiv")).then(canvas => {
var dataURL = canvas.toDataURL( "image/png" );
var data = atob( dataURL.substring( "data:image/png;base64,".length ) ),
asArray = new Uint8Array(data.length);
for( var i = 0, len = data.length; i < len; ++i ) {
asArray[i] = data.charCodeAt(i);
}
var blob = new Blob( [ asArray.buffer ], {type: "image/png"} );
saveAs(blob, "photo.png");
});
}
I just used the code provided in html2canvas site, then i used this code to download the screenshot.

JavaScript reading and previewing multiple images

I have found code for reading multiple images on the
internet.
Here is the code:
HTML
<input id="browse" type="file" onchange="previewFiles()" multiple>
JavaScript
function previewFiles() {
var preview = document.querySelector('#preview');
var files = document.querySelector('input[type=file]').files;
function readAndPreview(file) {
// Make sure `file.name` matches our extensions criteria
if ( /\.(jpe?g|png|gif)$/i.test(file.name) ) {
var reader = new FileReader();
reader.addEventListener("load", function () {
var image = new Image();
image.height = 100;
image.title = file.name;
image.src = this.result;
preview.appendChild( image );
}, false);
reader.readAsDataURL(file);
}
}
if (files) {
[].forEach.call(files, readAndPreview);
}
}
I have a problem with it, as I do not fully understand what is happening and why it does not preview/seems like it is storing multiple files.

The main problem in the included code is that there is no element with the id preview (ref: var preview = document.querySelector('#preview');)
Adding this and it will work. However, you can skip FileReader as it isn't needed. Instead treat the File as a Blob (they are essentially the same) and use createObjectURL() with it - the performance and the memory footprint are significant better in case you want to display a high amount of images.
document.querySelector('#browse').onchange = function() {
var preview = document.querySelector('#preview');
[].forEach.call(this.files, function(file) {
if (/image\/.*/.test(file.type)) { // use any image format the browser can read
var img = new Image;
img.onload = remURL; // to remove Object-URL after use
img.style.height = "100px"; // use style, "width" defaults to "auto"
img.src = (URL || webkitURL).createObjectURL(file);
preview.appendChild(img); // add image to preview container
}
});
function remURL() {(URL || webkitURL).revokeObjectURL(this.src)}
};
<input id="browse" type="file" multiple>
<div id=preview></div> <!-- an element with this ID was missing -->

Your final lines of code:
if (files) {
[].forEach.call(files, readAndPreview);
}
Should do nothing. It goes for each over an empty array.
I think you were trying to do something like:
files.forEach(readAndPreview)
Which would actually go over all of the files in the files array and call readAndPreview for them.

how to save canvas as png image?

I have a canvas element with a drawing in it, and I want to create a button that when clicked on, it will save the image as a png file. So it should open up the save, open, close dialog box...
I do it using this code
var canvas = document.getElementById("myCanvas");
window.open(canvas.toDataURL("image/png"));
But when I test it out in IE9, a new window opens up saying "the web page cannot be displayed"
and the url of it is:
data:image/png;base64,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
Anyone know how to fix this?

try this:
var canvas = document.getElementById("alpha");
var dataURL = canvas.toDataURL("image/png");
var newTab = window.open('about:blank','image from canvas');
newTab.document.write("<img src='" + dataURL + "' alt='from canvas'/>");
This shows image from canvas on new page, but if you have open popup in new tab setting it shows about:blank in address bar.
EDIT:- though window.open("<img src='"+ canvas.toDataURL('image/png') +"'/>") does not work in FF or Chrome, following works though rendering is somewhat different from what is shown on canvas, I think transparency is the issue:
window.open(canvas.toDataURL('image/png'));

FileSaver.js should be able to help you here.
var canvas = document.getElementById("my-canvas");
// draw to canvas...
canvas.toBlob(function(blob) {
saveAs(blob, "pretty image.png");
});

To accomodate all three points:
button
save the image as a png file
open up the save, open, close dialog box
The file dialog is a setting in the browser.
For the button/save part assign the following function, boiled down from other answers, to your buttons onclick:
function DownloadCanvasAsImage(){
let downloadLink = document.createElement('a');
downloadLink.setAttribute('download', 'CanvasAsImage.png');
let canvas = document.getElementById('myCanvas');
let dataURL = canvas.toDataURL('image/png');
let url = dataURL.replace(/^data:image\/png/,'data:application/octet-stream');
downloadLink.setAttribute('href', url);
downloadLink.click();
}
Example on Codepen
Another, somewhat cleaner, approach is using Canvas.toBlob():
function DownloadCanvasAsImage(){
let downloadLink = document.createElement('a');
downloadLink.setAttribute('download', 'CanvasAsImage.png');
let canvas = document.getElementById('myCanvas');
canvas.toBlob(function(blob) {
let url = URL.createObjectURL(blob);
downloadLink.setAttribute('href', url);
downloadLink.click();
});
}
Example on Codepen
Neither solution is 100% cross browser compatible, so check the client

I used this solution to set the file name:
HTML:
Download!
<canvas id="canvas"></canvas>
JavaScript:
function download(){
document.getElementById("downloader").download = "image.png";
document.getElementById("downloader").href = document.getElementById("canvas").toDataURL("image/png").replace(/^data:image\/[^;]/, 'data:application/octet-stream');
}

I had this problem and this is the best solution without any external or additional script libraries:
In Javascript tags or file create this function:
We assume here that canvas is your canvas:
function download(){
var download = document.getElementById("download");
var image = document.getElementById("canvas").toDataURL("image/png")
.replace("image/png", "image/octet-stream");
download.setAttribute("href", image);
}
In the body part of your HTML specify the button:
<a id="download" download="image.png"><button type="button" onClick="download()">Download</button></a>
This is working and download link looks like a button. Tested in Firefox and Chrome.

I maybe discovered a better way for not forcing the user to right click and "save image as". Live draw the canvas base64 code into the href of the link and modify it so the download will start automatically. I don't know if it's universally browser compatible, but it should work with the main/new browsers.
var canvas = document.getElementById('your-canvas');
if (canvas.getContext) {
var C = canvas.getContext('2d');
}
$('#your-canvas').mousedown(function(event) {
// feel free to choose your event ;)
// just for example
// var OFFSET = $(this).offset();
// var x = event.pageX - OFFSET.left;
// var y = event.pageY - OFFSET.top;
// standard data to url
var imgdata = canvas.toDataURL('image/png');
// modify the dataUrl so the browser starts downloading it instead of just showing it
var newdata = imgdata.replace(/^data:image\/png/,'data:application/octet-stream');
// give the link the values it needs
$('a.linkwithnewattr').attr('download','your_pic_name.png').attr('href',newdata);
});
You can wrap the <a> around anything you want.

Submit a form that contains an input with value of canvas toDataURL('image/png') e.g
//JAVASCRIPT
var canvas = document.getElementById("canvas");
var url = canvas.toDataUrl('image/png');
Insert the value of the url to your hidden input on form element.
//PHP
$data = $_POST['photo'];
$data = str_replace('data:image/png;base64,', '', $data);
$data = base64_decode($data);
file_put_contents("i". rand(0, 50).".png", $data);

Try this:
jQuery('body').after('<a id="Download" target="_blank">Click Here</a>');
var canvas = document.getElementById('canvasID');
var ctx = canvas.getContext('2d');
document.getElementById('Download').addEventListener('click', function() {
downloadCanvas(this, 'canvas', 'test.png');
}, false);
function downloadCanvas(link, canvasId, filename) {
link.href = document.getElementById(canvasId).toDataURL();
link.Download = filename;
}
You can just put this code in console in firefox or chrom and after changed your canvas tag ID in this above script and run this script in console.
After the execute this code you will see the link as text "click here" at bottom of the html page. click on this link and open the canvas drawing as a PNG image in new window save the image.

Full Working HTML Code. Cut+Paste into new .HTML file:
Contains Two Examples:
Canvas in HTML file.
Canvas dynamically created with Javascript.
Tested In:
Chrome
Internet Explorer
*Edge (title name does not show up)
Firefox
Opera
<!DOCTYPE HTML >
<html lang="en">
<head>
<meta charset="UTF-8">
<title> #SAVE_CANVAS_TEST# </title>
<meta
name ="author"
content="John Mark Isaac Madison"
>
<!-- EMAIL: J4M4I5M7 -[ＡＴ]- Hotmail.com -->
</head>
<body>
<div id="about_the_code">
Illustrates:
<ol>
<li>How to save a canvas from HTML page. </li>
<li>How to save a dynamically created canvas.</li>
</ol>
</div>
<canvas id="DOM_CANVAS"
width ="300"
height="300"
></canvas>
<div id="controls">
<button type="button" style="width:300px;"
onclick="obj.SAVE_CANVAS()">
SAVE_CANVAS ( Dynamically Made Canvas )
</button>
<button type="button" style="width:300px;"
onclick="obj.SAVE_CANVAS('DOM_CANVAS')">
SAVE_CANVAS ( Canvas In HTML Code )
</button>
</div>
<script>
var obj = new MyTestCodeClass();
function MyTestCodeClass(){
//Publically exposed functions:
this.SAVE_CANVAS = SAVE_CANVAS;
//:Private:
var _canvas;
var _canvas_id = "ID_OF_DYNAMIC_CANVAS";
var _name_hash_counter = 0;
//:Create Canvas:
(function _constructor(){
var D = document;
var CE = D.createElement.bind(D);
_canvas = CE("canvas");
_canvas.width = 300;
_canvas.height= 300;
_canvas.id = _canvas_id;
})();
//:Before saving the canvas, fill it so
//:we can see it. For demonstration of code.
function _fillCanvas(input_canvas, r,g,b){
var ctx = input_canvas.getContext("2d");
var c = input_canvas;
ctx.fillStyle = "rgb("+r+","+g+","+b+")";
ctx.fillRect(0, 0, c.width, c.height);
}
//:Saves canvas. If optional_id supplied,
//:will save canvas off the DOM. If not,
//:will save the dynamically created canvas.
function SAVE_CANVAS(optional_id){
var c = _getCanvas( optional_id );
//:Debug Code: Color canvas from DOM
//:green, internal canvas red.
if( optional_id ){
_fillCanvas(c,0,255,0);
}else{
_fillCanvas(c,255,0,0);
}
_saveCanvas( c );
}
//:If optional_id supplied, get canvas
//:from DOM. Else, get internal dynamically
//:created canvas.
function _getCanvas( optional_id ){
var c = null; //:canvas.
if( typeof optional_id == "string"){
var id = optional_id;
var d = document;
var c = d.getElementById( id );
}else{
c = _canvas;
}
return c;
}
function _saveCanvas( canvas ){
if(!window){ alert("[WINDOW_IS_NULL]"); }
//:We want to give the window a unique
//:name so that we can save multiple times
//:without having to close previous
//:windows.
_name_hash_counter++ ;
var NHC = _name_hash_counter ;
var URL = 'about:blank' ;
var name= 'UNIQUE_WINDOW_ID' + NHC;
var w=window.open( URL, name ) ;
if(!w){ alert("[W_IS_NULL]");}
//:Create the page contents,
//:THEN set the tile. Order Matters.
var DW = "" ;
DW += "<img src='" ;
DW += canvas.toDataURL("image/png");
DW += "' alt='from canvas'/>" ;
w.document.write(DW) ;
w.document.title = "NHC"+NHC ;
}
}//:end class
</script>
</body>
<!-- In IE: Script cannot be outside of body. -->
</html>

I really like Tovask's answer but it doesn't work due to the function having the name download (this answer explains why). I also don't see the point in replacing "data:image/..." with "data:application/...".
The following code has been tested in Chrome and Firefox and seems to work fine in both.
JavaScript:
function prepDownload(a, canvas, name) {
a.download = name
a.href = canvas.toDataURL()
}
HTML:
Download
<canvas id="canvasId"></canvas>

My solution via vue and async support
async downloadImage () {
const canvas = this.$refs.canvas
const blob = await new Promise(resolve => canvas.toBlob(resolve))
const downloadLink = document.createElement('a')
downloadLink.href = window.URL.createObjectURL(blob)
downloadLink.download = 'mycanvasimage.png'
downloadLink.click()
}

var canvasId = chart.id + '-canvas';
var canvasDownloadId = chart.id + '-download-canvas';
var canvasHtml = Ext.String.format('<canvas id="{0}" width="{1}" height="{2}"></canvas><a id="{3}"/>',
canvasId,
chart.getWidth(),
chart.getHeight(),
canvasDownloadId);
var canvasElement = reportBuilder.add({ html: canvasHtml });
var canvas = document.getElementById(canvasId);
var canvasDownload = document.getElementById(canvasDownloadId);
canvasDownload.href = chart.getImage().data;
canvasDownload.download = 'chart';
canvasDownload.click();