Question

This is to check if a user is opening another div (form; there are four for the page) without having saved the entry or update for the current form.

I need to compare the current value of dropdowns to all the possible choices of the dropdowns. If there is a difference the user is shown an alert notifying of having not saved the data. There is a not a set number of dropdowns. My script has been able to correctly count the number of dropdowns for each form.

Thanks,

James

Answer 1

You can do this by updating a variable on change of your select and then checking that value whenever you do what it is you do to move on to the next form. Here’s the code I have mocked up:

HTML –

<select id="one">
    <option value=""></option>
    <option>1</option>
    <option>2</option>
</select>
<br />
<select id="two">
    <option value=""></option>
    <option>3</option>
    <option>4</option>
</select>
<br />
<select id="three">
    <option value=""></option>
    <option>5</option>
    <option>6</option>
</select>
<br />
<!-- The submit buttons -->
<input type="submit" id="submit" value="Save" />
<br />
<!-- The link that moves on to the next form -->
<a href="#" id="moveOn">Move on</a>

Javascript –

// the variable
var selectChanged = false;
// set up everything on load
window.onload = function() {

    // bind handlers to submit button, link, an dselects
    document.getElementById("submit").onclick = submitForm;
    document.getElementById("moveOn").onclick = moveOn;

    var selects = document.getElementsByTagName("select");
    var numSelects = selects.length;
    for (var i = 0; i < numSelects; i++) {
        selects[i].onchange = noteChanged;
    }
}

function submitForm() {
    // set the changed variable to false
    selectChanged = false;
}

function moveOn() {
    // if the select has changed without save, alert the user and prevent
    // link actions
    if (selectChanged) {
        alert("You have changed a form value but not saved it");
        return false;
    }
}

// update the value for each time a select changes
function noteChanged() {
    selectChanged = true;
}

Here it is in action