Is it possible to call a function from functions.php in custom page or blog post?

I put simple function in functions.php:

function testTest()
echo "Test";

And called it from the page:

<?php testTest();?>

But it doesn't work. Do I need to make a plugin to use simple function like that inside one chosen custom page?

Thanks for your answer, Mary


You could use add_shortcode if you want to use it within the editor.

function footag_func() {
    return "Test";
add_shortcode( 'footag', 'footag_func' );

And then use [footag] in your editor.


Use code like this in functions.php and add a conditional tag

add_action( 'loop_start', 'your_function' );
function your_function() {
if ( is_singular('post') ) {
    echo 'Test';


Create a function in functions.php

function your_function() {
return 'Test';


And then use this in your template

echo your_function();
  • 1
    Thanks a lot! I will check all of the versions. I upvoted, but unfortunately it doesn't show because I'm a new user. Thanks once again! – Mary Jul 2 '19 at 9:08

You can quickly create a quick shortcode for doing that.

add_shortcode( 'test_shortcode', 'my_test_callback' );

Then, in the callback function you do this:

function my_test_callback() {
    //start adding the echoed content to the output buffer

    //run your code here - in this case your testTest() function

    //return the output buffer
    //NOTE: directly echoing the content will give unexpected results
    return ob_get_clean();

Then, in your content pages you just add [test_shortcode] and it will run your PHP function.

For a better view on shortcodes here are some useful links:

Official Shortcode API

A nice tool for creating shortcodes

An article I wrote on how to build shortcodes

  • 1
    Thanks a lot! I will check that. I upvoted, but unfortunately it doesn't show because I'm a new user. – Mary Jul 2 '19 at 9:09
  • no worries. hope that helped :) – Cornel Raiu Jul 2 '19 at 9:10
  • Hi @CornelRaiu - Is there a way to create a normal link on frontend, that upon clicking, runs "test_shortcode" or "my_test_callback()" function? – Ramin Arabbagheri May 20 '20 at 11:12
  • 1
    @RaminArabbagheri you should make use of AJAX for that. Make an on click listener on the button that will trigger an AJAX action and then output the response – Cornel Raiu May 20 '20 at 20:48

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