Unity - communicating with clientside Javascript and ajax. How to pass data back to the webpage from unity?

Here are two methods. One is, in my opinion, easier, but it is deprecated and you should ~not~ use it. Options two is the 'corrrect' way, but it is kinda ugly imo.

Option 1: Application.ExternalCall


This option allows you to call browser javascript directly, but Unity has deprecated support for it and is probably a bad idea for anything long term.

In a given browser with a Unity web player working, consider the following: In browser source, define a javascript function

<other html>
function foo(msg) {

In Unity, whenever it is nessecary:

Application.ExternalCall( "foo", "The game says hello!" );

This allows Javascript to be called from Unity. There is similar functionality for communication in the opposite direction.

Option 2: jslibs


This is the unity-endorsed way of doing things. It involved packaging javascript libraries into your games.

First, create a javascript file that will be packaged with your game. Here is an example file:

// Unity syntactic sugar
mergeInto(LibraryManager.library, {
    // Declare all your functions that can be called from c# here
    alert_user: function (msg) {
    other_func: function () {
     // does something else
     // etc.
     // put as many functions as you'd like in here

Place that file, with extension .jslib in your Plugins folder on your project.

Then, in your c# files, you need to:

// Declare a monobehavior, whatever
using UnityEngine;
using System.Runtime.InteropServices;

public class NewBehaviourScript : MonoBehaviour {

    // You have to declare the javascript functions you'll be calling
    // as private external function in your c# file. Additionally,
    // They need a special function decorator [DllImport("__Internal")]
    // Example:
    private static extern void alert_user(string msg);

    // With that unpleasantness over with, you can now call the function
    void Start() {
        alert_user("Hello, I am a bad person and I deserve to write c#");

Et viola. You can call other javascript from your c# javascript, and interact with the dom, but I will leave all those decisions up to you.

The other direction

In both cases, communication in the opposite direction (browser saying something to Unity) is the same format.

In javascript, create a UnityInstance (the way of this is a little two long-winded to put into this answer, check either docs). Then, just .sendMessage.

e.g.: c#

void DoSomething (string msg) {
    // this is a c# function that does something in the game
    // use your imagination


let game = UnityLoader // Actually load the game here
game.SendMessage('TheNameOfMyGameObject', 'DoSomething', 'This is my message');