How Pass C# Object to JavaScript?

mergeInto(LibraryManager.library, {

Hello: function () {
window.alert("Hello, world!");
},

HelloString: function (str) {
window.alert(Pointer_stringify(str));
},

PrintFloatArray: function (array, size) {
for(var i = 0; i < size; i++)
console.log(HEAPF32[(array >> 2) + i]);
},

AddNumbers: function (x, y) {
return x + y;
},

StringReturnValueFunction: function () {
var returnStr = "bla";
var bufferSize = lengthBytesUTF8(returnStr) + 1;
var buffer = _malloc(bufferSize);
stringToUTF8(returnStr, buffer, bufferSize);
return buffer;
},

BindWebGLTexture: function (texture) {
GLctx.bindTexture(GLctx.TEXTURE_2D, GL.textures[texture]);
},

});

Then you can call these functions from your C# scripts
like this:

using UnityEngine;
using System.Runtime.InteropServices;

public class NewBehaviourScript : MonoBehaviour {

[DllImport("__Internal")]
private static extern void Hello();

[DllImport("__Internal")]
private static extern void HelloString(string str);

[DllImport("__Internal")]
private static extern void PrintFloatArray(float[] array, int size);

[DllImport("__Internal")]
private static extern int AddNumbers(int x, int y);

[DllImport("__Internal")]
private static extern string StringReturnValueFunction();

[DllImport("__Internal")]
private static extern void BindWebGLTexture(int texture);

void Start() {
Hello();

HelloString("This is a string.");

float[] myArray = new float[10];
PrintFloatArray(myArray, myArray.Length);

int result = AddNumbers(5, 7);
Debug.Log(result);

Debug.Log(StringReturnValueFunction());

var texture = new Texture2D(0, 0, TextureFormat.ARGB32, false);
BindWebGLTexture(texture.GetNativeTextureID());
}
}

Above its OK
but i want pass object or class to javascript it error!!
how pass object or class to javascript??
thansks u help^^

example:

javascript

HelloObj: function (obj) {
window.alert("Hello, world!");
}

C#
public class Data {
public string s1 = "123";
public string s2;
}
[DllImport("__Internal")]
private static extern void HelloObj(object obj);

HelloObj(new Data());