JS downloads files according to binary data

The logic is simple , Go straight to the code

var xhr = new XMLHttpRequest()
xhr.open('get', '${ctx!}/admin/v1/licence/' + id)
xhr.responseType = "blob" //  Set the response data type to blob,  If not set, the downloaded file will be larger than the source file 
xhr.send()
xhr.onload = function() {
    
	var blob = new Blob([this.response], {
     type: this.responseType }); // ArrayBuffer , mime type 
	// console.log(this.response.length, blob.size)
	var a = document.createElement('a');
	var url = window.URL.createObjectURL(blob);
	a.href = url;
	a.download = 'license.lic';
	a.click();
}