为什么我的 php 认为数组是字符串？

Question

I have this frontend javascript code, that collects information (an array) and sends it to the backend. And for some reason, my php code believes this array is actually a string. Here is my javascript code:

function gamesearch() {

    var text_search = document.getElementById("search-space").value;
    var creator_search = document.getElementById("search-space-creator").value;
    var tags = document.getElementsByClassName("selectedtag");

    var tagarray = ['banana', 'fruit'];

    console.log(tagarray);
    var fd = new FormData();
    fd.append("text_search", text_search);
    fd.append("creator_search", creator_search);
    fd.append("tagarray", tagarray);
    fd.append("gamesearch", true);
    var xhr = new XMLHttpRequest();
    var fullurl = '../backend/gamesearch.php';
    xhr.open('POST', fullurl, true);
    xhr.onload = function() {
        if (this.status == 200) {

            console.log(this.responseText);

        };
    };
        xhr.send(fd);

}

And here is my backend php code

if (isset($_POST['gamesearch'])) {
  $text_search = $_POST['text_search'];
  $creator_search = $_POST['creator_search'];
  $tagarray = $_POST['tagarray'];

echo gettype($tagarray);

}

And in the console it says: string. Please help! Thanks!

Answer 1

Try stringifying your JSON array before sending it to the backend.

fd.append("tagarray", JSON.stringify(tagarray));

Then decode it back again in the backend

$tagarray = json_decode($_POST['tagarray']);