Print preview freeze intervals in javaScript
Question
I have a problem with method mywindow,print(); cause when print preview is open my intervals in JavaScript files stops. My code is :
function pri() {
var mywindow = window.open('bileta.html', 'hello', 'height=400,width=600');
mywindow.document.write('<html><head><title></title>');
mywindow.document.write('</head><body >');
mywindow.document.write('<h1></h1>');
mywindow.document.write(document.getElementById("hello").innerHTML);
mywindow.document.write('</body></html>');
mywindow.document.close(); // necessary for IE >= 10
mywindow.focus(); // necessary for IE >= 10*/
mywindow.print();
mywindow.close();
return true;
}
I've searched in google and stalckoverflow but all the answers were about the chrome version and I use a chrome version 58.0.3029.110 (64-bit).
So what I'm asking is that is any way to print and my print preview page not freeze my JavaScript intervals?
1 answers
solution1
0 2017-06-01 21:38:40
As mentioned in my comment above I believe the single thread of Javascript is blocked by the window.print() call you are making so a normal interval you set will pause.
A web worker opens a second thread up, that can still keep it running. My script looks like this:
<!doctype html>
<html>
<head></head>
<body>
<p>Press to <a href="javascript:pri()">print</a>!</p>
<p id="countup">Count</p>
<script>
window.onload = function() {
if (window.Worker) {
var myWorker = new Worker('worker.js');
myWorker.onmessage = function(msg) {
console.log(msg.data);
document.getElementById('countup').innerHTML = msg.data;
};
}
}
function pri() {
var mywindow = window.open('bileta.html', 'hello', 'height=400,width=600');
mywindow.document.write('<html><head><title></title>');
mywindow.document.write('</head><body >');
mywindow.document.write('<h1 id="hello">Hello</h1>');
mywindow.document.write('</body></html>');
mywindow.document.close(); // necessary for IE >= 10
mywindow.focus(); // necessary for IE >= 10*/
mywindow.print();
mywindow.close();
return true;
}
</script>
</body>
</html>
And the worker.js script looks like this:
function counter() {
var count = 0;
self.setInterval(function() {
postMessage('counter =' + count);
count++;
}, 100);
}
counter();
Of course printing involves interacting with the browser and OS so results may vary. This script works with Chrome, IE11, Edge on Windows 10 but not Firefox (perhaps somebody could post a comment fixing that.)
See these two articles for more information on web workers:
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