Tim Saunders Tim Saunders - 6 days ago 6
Javascript Question

Is there a plugin or example of a jquery slider working with non-equably divisible values?

I have found two excellent jquery plugins for generating a slider for a web form, which degrade nicely in browsers that do not support javascript have styles turned off etc.

The first is the Jquery.UI version : http://ui.jquery.com/demos/slider/#steps

The second is a select element to slider : http://www.filamentgroup.com/lab/update_jquery_ui_16_slider_from_a_select_element/

However I need to create a slider that doesn't just divide the slider up in equal parts.

For example let's say I have the following range of numbers:

800,1000,1100,1200,1300,1400,1500

I'd like the slider to have a nice big gap between 800 and 1000 then smaller gaps between 1100-1500

So the slider would look a little like this:

800----1000--1100--1200--1300--1400--1500

Preferably I'd like it to degrade to a drop down, so the question is does anyone know of a plugin that supports this or has any recommendations for the best way of achieving this, customise the filamentgroup plugin roll my own etc.

Update: Been hacking about with filament group's slider and it implements the handles via JQuery UI's slider anyway. So it looks like modding JQuery.UI its self is the only option available. Will dig about in the code to see if I can find the requisite bit that needs changing. If in the meantime anyone has any ideas!!!

Answer

You could do it using jquery's slider by hooking into the slide event (effectively overriding it)... Something like this:

$(function() {
    var values = [0, 10, 50, 60, 70, 80, 90, 91, 92, 93, 94, 95, 100];
    var slider = $("#slider").slider({
        slide: function(event, ui) {
            var includeLeft = event.keyCode != $.ui.keyCode.RIGHT;
            var includeRight = event.keyCode != $.ui.keyCode.LEFT;
            slider.slider('option', 'value', findNearest(includeLeft, includeRight, ui.value));
            return false;
        }
    });
    function findNearest(includeLeft, includeRight, value) {
        var nearest = null;
        var diff = null;
        for (var i = 0; i < values.length; i++) {
            if ((includeLeft && values[i] <= value) || (includeRight && values[i] >= value)) {
                var newDiff = Math.abs(value - values[i]);
                if (diff == null || newDiff < diff) {
                    nearest = values[i];
                    diff = newDiff;
                }
            }
        }
        return nearest;
    }
});

Should work for what you describe... I've tested it for dragging with the mouse & using left/right/home/end keys (obviously you'd need to change the left/right to up/down if you want a vertical slider).

Some notes:

  • Obviously the values array is whatever steps you want for your purposes.
  • Also obviously, the above code assumes a div with an id of "slider" to work.
  • It will probably work strangely if your min/max values are not the same as your min/max values for the slider (I would suggest just using "min: values[0], max: values[values.length - 1]" as your min/max options on the slider & then you should always be safe).
  • Obviously this option won't currently degrade to a drop down list, but it would be very easy to do... simply render your choices as a normal drop down list (the default state incase of no javascript) & then use jquery to hide the drop down list and also create your values array based on the options. Then you could just update the (hidden) drop down list at the same time as you update the slider in the code above, so that when your form posts, the correct value will be selected in the drop down list.

Hope that helps.

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