Wordpress Theming: add custom scripts and jquery the correct way

Question

Just took over a wordpress project. The former developers screwed up the theming so it prevents my ajax forms (gravityform) from working correctly. Proplem is the way they add jquery and custom js in header.php:

    <script type="text/javascript" src="<?php bloginfo('template_url'); ?>/js/jquery.easing.1.3.js"></script>
    <script type="text/javascript" src="<?php bloginfo('template_url'); ?>/js/slides.min.jquery.js"></script>
    <script type="text/javascript" src="<?php bloginfo('template_url'); ?>/js/script.js"></script>
    <script type="text/javascript" src="<?php bloginfo('template_url'); ?>/js/tabs.min.js"></script>

I am totaly new to wordpress theming thought, how would I correctly add those scripts in my functions.php using wp_register_script and wp_enqueue_script.

How do I find out which script depends on the others? like the correct order of calling them?

EDIT I made it to include the scripts the proper way via wp_enqueue_scripts. But now I am facing strange JS errors. TypeError: $ is not a function

It works when I substitute the $ by jQuery. But this cant be a solution. Why does this error appear anyways?

Answer 1

The best way to avoid asset conflicts is by properly enquing the files. To do this you must use wp_enqueue_script

a good way to do this is to put it as part of a function in your functions.php file like so

1. create a function
2. insert wp_register_script into the function
3. then insert wp_enqeue_script into the function
4. use add_action(), to initlize the enqueue-ing process

---

so -

function load_scripts() {
  wp_register_script( 'script-name', get_template_directory_uri() . '/js/script.js', array( 'scriptyouwillwaittobeloaded' ) );
  wp_enqueue_script( 'script-name' );
}

add_action('wp_enqueue_scripts', 'load_scripts');

---

In this example the function load_scripts() would then be called in the header.php file. Take a look at wp_register_script as well to get a better understanding of the arguments for that as well, but in summary -

first argument: is the name you want to use as reference to this script

second argument: is the actual link to the script

third argument: is the script that you want to load before this script (the script you want to wait for before this script loads)

---

and for wp_enqueue_script, the argument is merely a reference to the name (the first argument of wp_register_script)

---

the add_action function arguments:

first argument: the function you are "hooking" into

second argument: the function you created that will be "hooked"

---

To note - you can load as many scripts as you would like in this function, this is just an example of loading a single script.

Answer 2

What it looks like the dev's did was just to use a simple reference. If you would like to enqueue a WP script look at wp_enqueue_script

I don't believe the scripts will depend on anything other than a specific version of jquery.

this is how they do it:

<?php

function my_scripts_method() {
    wp_enqueue_script(
    'custom-script',
    get_stylesheet_directory_uri() . '/js/custom_script.js',
    array( 'jquery' )
    );
}

add_action( 'wp_enqueue_scripts', 'my_scripts_method' );

?>