Javascript set value by document ID

Question

What I would like to do is if there is clicked at the 'reset' button, the value of a other button changes. I tried to use the document.getelementbyid property but it seems not to work. Does somebody know how I should implement this?

function reset() {
    stop();
    x.reset();
    update();
    opnieuw = setTimeout(function(){
    document.getElementById("scherm3").style.display = "block";
     document.getElementById("scherm2.2").style.visibility = "hidden"; 
     }, 10000);    
    clearTimeout(timeOut);
    clearTimeout(timeOutElse);
    document.getElementById("buttontimer").value = "Start";
} 

setTimeout(start, 5000);

function toggleTimer(event) {
 if (isTimerStarted) {
    stop();
    event.target.value = 'Start';
    timeOut = setTimeout(function(){
    document.getElementById("scherm4").style.visibility = "visible";
     document.getElementById("scherm2.2").style.visibility = "hidden"; 
     }, 4000)
    clearTimeout(opnieuw);
    clearTimeout(timeOutElse);
    }
     else {
    start();
    event.target.value = 'Stop';
    timeOutElse = setTimeout(function(){
    document.getElementById("scherm3").style.display = "block";
     document.getElementById("scherm2.2").style.visibility = "hidden";
    }, 8000)
          clearTimeout(timeOut);
    clearTimeout(opnieuw);
  }
}

and HTML:

<div id="button1"><input type="button" value="Stop" onclick="toggleTimer(event); clicks5times();" id="buttontimer"></div>       
        <input type="button" value="Opnieuw" onclick="reset()" class="button2" id="opnieuw">  

Answer 1

You could probably just make your code simpler by simply having a "Start" and "Stop" button, separately, and just show/hide the correct button for the current context. You are already (sort of) doing this, by showing the "Reset" button. Just make this a "Stop" button. When they click "Start", the "Start" button is hidden and the "Stop" button is shown. Click "Stop", and "Stop" is hidden and "Start" is shown. You could even use a global boolean to track state and make the "Stop" button behave like a "Pause" button, and show an additional "Reset" button that puts the timer back to 0. That all depends on what, exactly, you are trying to accomplish.