Javascript警报不停留在Mozilla firefox中

Question

I wrote an alert which comes on change of a dropdown. It comes for a particular value selected on the dropdown. The alert is working fine in IE, but in Mozilla it stays for a moment and disappears.

Below is the code for alert which gets called on onchange of a dropdown.

function psychAlert()
{
    var element = document.getElementById("service_help");
    for (var x = 0; x <element.options.length; x++) {
        if (element.options[x].selected) {
            selectedVal = element.options[x].value;
            break;
        }
    }

    if(selectedVal == '1514'){
        alert("Please call Helpline");
    }
}

Below is the dropdown code where the alert is getting called from a onchange.

<html:select tabindex="<%= tabIndex.getNext()%>" property="serviceDesc" size="1" styleId="service_help" onchange="javascript:  psychAlert(); " ></html:option>
    html:optionsCollection property="serviceDescList" value="lookupCode" label="shortDescription"/>
<html:select>

Answer 1

Because your example doesn't include the actual data within your dropdown list, I cleaned it up and made an example that's much easier to follow and should clarify any issues you're having. This code has been tested in IE 8, Firefox, and Chrome, and works without fail in all three.

 var example = document.getElementById("dlExample"); example.addEventListener("change", function() { if (example.value === "3") { alert("Please call the help desk."); } }); 

 <select id="dlExample"> <option value="0">Hi</option> <option value="1">Bye</option> <option value="2">Yes</option> <option value="3">No</option> </select> 

So looking at this code. First, we simplified your very convoluted and overly done select . Now you're no longer calling an onchange within the code, storing the value there, or requiring needless loops. A simple select with all of your options.

As for the javascript, we started by first adding a simple EventListener by finding the select with a getElementsByID (note that I set the ID in the select , the name wouldn't won't work). After that, we set the EventLIstener to be based off a change event. Anyone a change happens to that dropdown, it will check and verify that the dropdown value is whatever you wanted the alert to be called upon. Sometimes simple is better, and in this case, even more so.