在Wordpress上放置自定义PHP和JQuery代码的位置？

I am really new to Wordpress but not to web development.

I am creating a wordpress based website, I have a youtube channel with more than 450 videos, and I would like to create a post for each one of them.

I already have an API KEY for Youtube API Data V3 and the right url to bring my videos. Also, I read about this great wp_insert_post that seems to do exactly what I need to do.

What I want to know is where to put my code? It will be very simple, something like: Clientside:

$.get('https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&maxResults=50&playlistId=UUbRrCTEldKci2yWosUukSQQ&key=APIKEY');
.success(function(data){
    data.forEach(function(vid){
        $.post('myPhpPostInserter.php', vid);
    });
});

Server Side:

<?php
$myPost['title'] = $_POST['vid_title'];
//some more mapping on the $myPost array...
wp_insert_post($myPost);

This will be a one-time job, so I am trying to implement this quick client-server solution.

the usual place is in functions.php in your theme or child theme (recommended as updates will overwrite custom code in your theme) or a plugin you create yourself (pluginname.php).

I have put the best way to achieve this below, its not client side at all but I believe this will suit you better. Basically on every page load the code will run and upload the next 50 videos (if timing out reduce the figure below -- see comments) (you should remove the code when all videos are uploaded).

Also excuse me if there are any errors, typed this out on a txt file. Also i dont know the structure of the json returned, i dont have a api key to check, you will need to update the correct structure in the for loop to get the data you want...

function upload_videos(){


    if(!get_option( 'vid_count' ) ){
        $x=0;
        update_option( 'vid_count', $x );
    } else {
        $x= (int) get_option('vid_count');
    }

    //might as well cache the file to speed things up
    if( !file_exists ( 'videos.json' )){

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_URL, 'https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&maxResults=5000&playlistId=UUbRrCTEldKci2yWosUukSQQ&key=APIKEY');
        $json = curl_exec($ch);
        curl_close($ch);

        $videos = fopen("videos.json", "w") or die("Unable to open file!");
        fwrite($videos, $json);
        fclose($videos);
        unset($videos);
    }

    $videos =  fopen("videos.json", "r");
    $videos = json_decode($videos);


    //get the structure of the array here and update the foreach loop to the right place in the object...
    //remove this code when ready.....
    var_dump($videos);
    exit;
    //end remove.....


    /*
        remember to update to the correct values....
        we will do 50 at a time
    */
    $max= $x+50; // adjust 50 downwards if needed

    if($max > count( $videos['list'] ) )
        $max= count( $videos['list'] );

    if($max > $x)
        return;


    update_option('vid_count', $max );

    for($v=$x; $v<=$max; $v++){

        $id= wp_insert_post(
        array(
            'post_status'=>'publish',
            'post_type'=>'video', //higher recommended to create a cpt and post template for this..
            'post_title'=> $videos['list'][$v]->title, // sample --- dont know the format of the returned object
            'content'=> 'whatever you want or html for the video, etc................'
        ));

        //save the url into the metadata of the post....we can use this in templates to show the video....
        update_post_meta($id, '_vid_url', $videos['list'][$v]->video_url);// sample --- dont know the format of the returned object

    }

}

add_action('init', 'upload_videos');