I'm a noobie and I need some help with changing events in textbox.

Here's the code I am working with:

```
    <body>
      <form action="#">
        <input type="text" id="begin" /> Apple
        =
        <input type="text" id="done" /> 

        <select id="newValue" onchange = "function()">
          <option value="a">Apple</option>
          <option value="b">Blueberry</option>
          <option value="c">Cheese</option>
        </select>
        <p id = "weight"></p>
      </form>

      <script>
      var apple = document.getElementById('begin'),
          choice = document.getElementById('done');

      apple.onkeyup = function(){
         var temp = document.getElementById("newValue").value;
          choice.value = this.value * 1; //if apple
         choice.value = this.value * 2; //if blueberry
         choice.value = this.value * 3; //if cheese
      }
</script>
</body>

```

I have two text boxes. The left text box ('begin') will accept the weight of apple. But the right box ('done') should change the number value depending on what the user chooses form the drop-down text list.
My 

```
apple.onkeyup = function(){

```

is not doing the right thing. If I give the value of '2' to the left text box,no matter what I choose in the dropdown list, it will return 2 \* 3 = 6, meaning it skips everything in the function and evaluates only the last statement.

```
choice.value = this.value * 3; /*if cheese

```

How I want it to work is:

```
Left Box : 2      Right Box : 2 (if apple was chosen)
Left Box : 2      Right Box : 4 (if blueberry was chosen)

```

I'm sure I need a few 'if statements' to determine which output choice was chosen, something along the lines of 

```
    if(temp = Apple){
       choice.value = this.value * 1;
    }else if(temp = Blueberry){
       choice.value = this.value * 2;
    }
   }  

```

The value in Right Box should also change as the user chooses a different item from the list..

Although I'm not sure if that's the right approach/syntax.