if (Application.isWebPlayer) {
    print("We are running this from inside of the web player!");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        if (Application.isWebPlayer)
            print("We are running this from inside of the web player!");
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        if Application.isWebPlayer:
            print('We are running this from inside of the web player!')