Cacher is the code snippet organizer for pro developers

//FRONTEND -- in questo caso il contenuto è deciso dal client (non dovevo scaricare un file "fisico" presente nel server, nel tuo caso basta togliere il content e settare il backend in modo appropriato -- vedi il codice backend sotto)

options = {
	filename	: filename,
	content		: content,
	script		: 'resources/download.php'
}



generateFile : function(options){
		options = options || {};
		if(!options.script || !options.filename || !options.content){
			throw new Error("Please enter all the required config options!");
		}

		// Creating a 1 by 1 px invisible iframe:

		var iframe = $('<iframe>',{
			width:1,
			height:1,
			frameborder:0,
			css:{
				display:'none'
			}
		}).appendTo('body');

		var formHTML = '<form action="" method="post">'+
			'<input type="hidden" name="filename" />'+
			'<input type="hidden" name="content" />'+
			'</form>';

		// Giving IE a chance to build the DOM in
		// the iframe with a short timeout:

		setTimeout(function(){

			// The body element of the iframe document:

			var body = (iframe.prop('contentDocument') !== undefined) ?
							iframe.prop('contentDocument').body :
							iframe.prop('document').body;	// IE

			body = $(body);

			// Adding the form to the body:
			body.html(formHTML);

			var form = body.find('form');

			form.attr('action',options.script);
			form.find('input[name=filename]').val(options.filename);
			form.find('input[name=content]').val(options.content);

			// Submitting the form to download.php. This will
			// cause the file download dialog box to appear.

			form.submit();
		},50);
	},





//BACKEND

<?php
if(empty($_POST['filename']) || empty($_POST['content'])){
	exit;
}

// Sanitizing the filename:
$filename = preg_replace('/[^a-z0-9\-\_\.]/i','',$_POST['filename']);

// Outputting headers:
header("Cache-Control: ");
header("Content-type: text/plain");
header('Content-Disposition: attachment; filename="'.$filename.'"');

echo $_POST['content'];
?>