How to download PDF automatically using js?

Use the download attribute.

var link = document.createElement('a');link.href = url;link.download = 'file.pdf';link.dispatchEvent(new MouseEvent('click'));

It is also possible to open the pdf link in a new window and let the browser handle the rest:

window.open(pdfUrl, '_blank');

or:

window.open(pdfUrl);

/* Helper function */function download_file(fileURL, fileName) {// for non-IEif (!window.ActiveXObject) {    var save = document.createElement('a');    save.href = fileURL;    save.target = '_blank';    var filename = fileURL.substring(fileURL.lastIndexOf('/')+1);    save.download = fileName || filename;       if ( navigator.userAgent.toLowerCase().match(/(ipad|iphone|safari)/) && navigator.userAgent.search("Chrome") < 0) {            document.location = save.href; // window event not working here        }else{            var evt = new MouseEvent('click', {                'view': window,                'bubbles': true,                'cancelable': false            });            save.dispatchEvent(evt);            (window.URL || window.webkitURL).revokeObjectURL(save.href);        }   }// for IE < 11else if ( !! window.ActiveXObject && document.execCommand)     {    var _window = window.open(fileURL, '_blank');    _window.document.close();    _window.document.execCommand('SaveAs', true, fileName || fileURL)    _window.close();}}

How to use?

download_file(fileURL, fileName); //call function

Source: convertplug.com/plus/docs/download-pdf-file-forcefully-instead-opening-browser-using-js/