БАЗА ЗНАНИЙ

function utf8_1251 (aa) {
    var bb = [], c = 0;
    for (var i = 0; i < aa.length; i++) {
        c = aa.charCodeAt(i);
        if (c > 127) {
            if (c > 1024) {
                if (c == 1025) {
                    c = 1016;
                } else if (c == 1105) {
                    c = 1032;
                } else if (c == 8470) {
                    c = 1033;
                }
                bb.push(c - 848);
            }
        } else {
            bb.push(aa.charCodeAt(i));
        }
    }
    return bb;
} 
 
 
function popup(data) {
 
	myarray=utf8_1251(data);
	data1=new Uint8Array(myarray);
 
	properties = {type: 'text/csv; charset=windows-1251'}; // Specify the file's mime-type.
	try {
	  // Specify the filename using the File constructor, but ...
	  file = new File([data1], "file.txt", properties);
	} catch (e) {
	  // ... fall back to the Blob constructor if that isn't supported.
	  file = new Blob([data1], properties);
	}
	url = URL.createObjectURL(file);
	document.getElementById('link').href = url;
 
        return true;
    }