按钮在单击调用jQuery函数和访问PHP

Question

I am very new to Wordpress and Woocommerce. I have few doubts wrt jquery in Wordpress. Say i have a function

function test(){
      alert("test");
      <?php
      error_log("Test ---------------------------- ", 0);
      ?>
  }

and a button:

<input type="button" id="btnclick" onclick="test();" value="Test" />`

error log is printing on page load but not on click. But i want to execute code inside php block only when user clicks on button.Is there a way to achieve this ? Thanks in advance`

Answer 1

jPO has already explained how to solve this in a good way, but I thought I should explain why this happens.

PHP is executed on the server. Once the page has been sent to the client, the PHP is no more. JavaScript happends on the client, and can be executed as long as the user is viewing the webpage. Since they do not live during the same timeperiod they are not aware of each other and can not be mixed in that way.

When you visit the page in your browser, the browser sends a request to the server. On the server the PHP interpreter goes through the code of the requested page, executing everything between <? and ?> . It does not understand what the other stuff around it is - it could be HTML, JS, plain text, anything, the PHP interpreter does not know and does not care. That is why it writes to the error log on page load.

When the PHP interpreter is done it has produced a document looking like this:

function test(){
      alert("test");
  }

That is sent to the client, and the JS (without any instruction to write to the error log) is run on the client when the button is pushed.

Answer 2

Not possible like that. If you'd like to do so. You need something like ajax method in php which you can call. Let's say you have a file in the root of your project called ajax.php, there you can define a function named test(), then you have to have a $_REQUEST translator, which calls your function test(), so the ajax.php would look like this

<?php
  // checks if you sent a parameter named method and calls the method
  // if you provide parameter named params it will send them too
  if(isset($_REQUEST)){
    if(isset($_REQUEST["params"]))
      ajax($_REQUEST["method"],$_REQUEST["params"]);
    else
      ajax($_REQUEST["method"]);
  }

  function ajax($function,$data = null){
    $function($data);
  }
  function test(){
    error_log("Test ---------------------------- ",0);
  }

and your ajax would look like this

function test(){
  $.ajax({
    url:"ajax.php",
    data:{
      method:"test"
    }
  });
}

hope it helps