= :

این عملگر برای مقداردهی یا assign یک مقدار به یک متغیر بکار برده می شود:

    var number = 100;  // Here number variable assigned using =

== :

این عملگر ، فقط محتوای دو متغیر را بررسی می کند که برابر باشند یا نه:

    if (number == 100)  // Here Comparision between two values using ==. It will compare irrespective of datatype of variable
       alert("Both are equal");    
    else    
       alert("Both are not equal");   

=== :

این عملگر ، هم مقدار و هم نوع (data type) دو عملگر را بررسی می کند:

    if (number === 100)  // Here Comparision between two values using ===. It will compare strict check means it will check datatype as well.
       alert("Both are equal");      
    else      
       alert("Both are not equal");     

تفاوت == و === را در 2 مثال زیر ببینید:

<h2>Difference between =, == and === in Javascript</h2>  
<script type="text/javascript">  
    function Comparision() {  
        var number = 100;  // Here number variable assigned using =  
        debugger;  
  
        if (number == 100)  // Here Comparision between two values using ==. This will not check datatype irrespective of datatype it will                                  do comparision  
            $("#lblMessage").text("Both are equal");  
        else  
            $("#lblMessage").text("Both are not equal");  
  
      if(number == "100")  //Here Comparision between two values using ==. This will not check datatype irrespective of datatype it will                              do comparision  
            $("#lblMessage1").text("Both are equal");  
        else  
           $("#lblMessage1").text("Both are not equal");  
    }  
</script> 

نتیجه اجرای کد بالا می شود این:

<h2>Difference between =, == and === in Javascript</h2>  
<script type="text/javascript">  
    function Comparision() {  
        var number = 100;  // Here number variable assigned using =  
        debugger;  
  
        if (number === 100)  // Here Comparision between two values using ==. This will not check datatype irrespective of datatype it 
                              will do comparision  
            $("#lblMessage").text("Both are equal");  
        else  
            $("#lblMessage").text("Both are not equal");  
  
        if (number === "100")  // Here Comparision between two values using ==. This will not check datatype irrespective of datatype it                                  will do comparision  
            $("#lblMessage1").text("Both are equal");  
        else  
           $("#lblMessage1").text("Both are not equal");  
    }  
</script>  
<table>  
    <tr>  
        <td>  
            100 === 100  
        </td>  
        <td>  
           <label id="lblMessage" runat="server" ></label>  
        </td>  
    </tr>  
    <tr>  
        <td>  
            100 === "100"  
        </td>  
        <td>  
           <label id="lblMessage1" runat="server" ></label>  
        </td>  
    </tr>  
      
</table>  
 <button id="btnSubmit" type="submit" onclick="Comparision();" class="btn btn-primary">  
                Submit</button>

نتیجه کد بالا هم می شود این: