Get the main js from function.php

// Register Script
function custom_scripts_main() {

	wp_deregister_script( 'main' );
	wp_register_script( 'main', '-child/script/main.js', false, false, true );
	wp_enqueue_script( 'main' );

}

// Hook into the 'wp_enqueue_scripts' action
add_action( 'wp_enqueue_scripts', 'custom_scripts_main' );