PHP

wordpress hook add javascript

add_action( 'wp_enqueue_scripts', 'my_custom_script_load' );
function my_custom_script_load(){
  wp_enqueue_script( 'my-custom-script', get_stylesheet_directory_uri() . '/custom-scripts', array( 'jquery' ) );
}

wordpress add javascript

add_action('wp_head', 'your_function_name');
function your_function_name(){
?>
<script>PASTE HEADER CODE HERE</script>
<?php
};