将数据从javascript发送到php以生成pdf但不起作用

Question

I am using JavaScript to take the info from a form completed by the user, then sending this data to PHP and generate a PDF with FPDF. The problem is I want the browser to ask the user to save the PDF or view it online but I cannot figure out how. The PDF generates correctly but only when I save it directly to a certain path specified by me.

The question is how do you guys send data from JavaScript to PHP to generate a PDF file then the browser asks the user to open or download, Or how can I make a function where the user can retrieve this PDF.

The JavaScript:

function senddata() {//this activates when i push a button not a submit
    var peticion = new XMLHttpRequest();
    peticion.open('POST', 'generatepdf.php');
    var nueva2 = {};
    var key;

    for (i = 0; i < 6; i++) {
        key = document.forms[0].elements[i].id;
        nueva2[key] = document.forms[0].elements[i].value;
    }//here i take my data from the form and make an object

    var json = JSON.stringify(nueva2);//here i tranform my object to json string so i can send it to my php

    var parametros = "json_string=" + json;//here I do this so later I can easily transform the $_POST to an array in the form json_decode($_POST["json_string"],true); 

    peticion.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

    peticion.send(parametros);//it sends ok
}

The PHP with the FPDF class and things

<?php

require('fpdf/fpdf.php');
require('functions.php');

if($_SERVER['REQUEST_METHOD']=='POST'){

    $datos=json_decode($_POST["json_string"],true); //here i have my data in an array format so i can use the parameters to fill my pdf fields

    //...lots of pdf things here...//

 $pdf->Output('F',"pdfs/Cotizacion ".$datos["nombres"]." ".$datos["apellidos"].".pdf");//this works but never ask the user
 //$pdf->Output('D',"pdfs/Cotizacion ".$datos["nombres"]." ".$datos["apellidos"].".pdf");//this should force a dowload or send to the browser but doesnt work
 //$pdf->Output();//this should send to the browser but doesnt work
    }

Answer 1

To view your PDF inline to the browser, you should use the I variable instead. View full documentation here.

Also I don't think outputting the file in two methods at the same time works. It might conflict each other. The best way to do that is to test each method and if it does conflict each other just simply add a condition for the user to decide whether he/she wants to download or view it in the browser. Hope this helps.