带有jQuery AJAX的PHP函数？

I have a question regarding, PHP functions, jQuery and AJAX. If I have a button in my php index like this:

    <input type="submit" value="Download" id="download"/>

And I have another php file (dubs.php) that contains this:

<?php
function first(){
    echo 'first';
}
function second(){
    echo 'second';  
}
?>

And my jQuery, like this:

$(document).ready(function(e) {
    $("#download").click(function(){
        $.ajax({
            type: "GET",
            url: "dubs.php",
        });
    });
});

How do I tell my AJAX request to select for example the second function?

I have no idea on how to do this, I've tried it with "success: first()" or with "success: function(){ first() }" but that did not work.

This is what I would do:

Your PHP:

<?php

function first(){
    echo 'first';
}

function second(){
    echo 'second';  
}



  if (isset($_POST["first"])) first();
  if (isset($_POST["second"])) second(); //add 'else' if needed

?>

your jQuery:

$.post("dubs.php", {"first":true}, function(result) {
  $("#someDivToShowText").text(result);
});

Then, according to the object you send to $.post, the php file will know which function to run.

Try this in your PHP page:

<?php

function first(){
    echo 'first';
}

function second(){
    echo 'second';  
}
switch($_POST['func']) {
    case "first":
    first();
    break;
    case "second":
    second();
    break;
    default:
    // Define your default here }
?>

and this in your JS:

$(document).ready(function(e) {

    $("#download").click(function(){
        $.ajax({
            type: "GET",
            url: "dubs.php",
            data: {'func':'first'}
        });
    });

The func variable will tell php which function to run!

});

why don't you try to pass with data:{func:f1} and get it on php side and if f1 is there then fire the first function. Although you can send multiple:

jQuery:

$("#download").click(function(e){
    e.preventDefault(); // <----stops the page refresh
    $.ajax({
        type: "GET",
        url: "dubs.php",
        data:{'func':'f1'}
    });
});

PHP:

<?php

  function first(){
     echo 'first';
  }

  function second(){
     echo 'second';  
  }


if(isset($_GET['func']=='f1'){
     first();
}else{
     second();
}

?>

JS

$("#download").click(function(){
    $.ajax({
        type: "GET",
        url: "dubs.php",
        data: {'function':'first'}
    });
});

PHP

call_user_func($_GET['function']);

NOTE
Be careful with $_GET parameters, better check first the contents of $_GET

In your ajax pass some params to identify which function you want to use like this

    $("#download").click(function(){
        $.ajax({
            type   : "POST",//If you are using GET use $_GET to retrive the values in php
            url    : "dubs.php",
            data   : {'func':'first'},
            success: function(res){
              //Do something after successfully completing the request if required
            },
            error:function(){
              //If some error occurs catch it here
            }
        });
    });

And in your php file

you can retrive the values in data send via ajax and do the following

if(isset($_POST['func']) && $_POST['func']=='first'){
    first();
}
else{
    second();
}