I'm trying to create custom events in JQuery that are supposed to detect when a scrollbar is clicked¹.
I know there's lots of text, but all my questions are boldfaced and there's a JSFiddle example you can work on straight away.

Because I haven't found any built in functionality for this,
I had to create a hasScroll function, checking if the element has a scrollbar,

$.fn.hasScroll = function(axis){
    var overflow = this.css("overflow"),
        overflowAxis;

    if(typeof axis == "undefined" || axis == "y") overflowAxis = this.css("overflow-y");
    else overflowAxis = this.css("overflow-x");

    var bShouldScroll = this.get(0).scrollHeight > this.innerHeight();

    var bAllowedScroll = (overflow == "auto" || overflow == "visible") ||
                         (overflowAxis == "auto" || overflowAxis == "visible");

    var bOverrideScroll = overflow == "scroll" || overflowAxis == "scroll";

    return (bShouldScroll && bAllowedScroll) || bOverrideScroll;
};

and an inScrollRange function, checking if the click performed was within the scroll range.

var scrollSize = 18;

function inScrollRange(event){
    var x = event.pageX,
        y = event.pageY,
        e = $(event.target),
        hasY = e.hasScroll(),
        hasX = e.hasScroll("x"),
        rX = null,
        rY = null,
        bInX = false,
        bInY = false

    if(hasY){
        rY = new RECT();
        rY.top = e.offset().top;
        rY.right = e.offset().left + e.width();
        rY.bottom = rY.top +e.height();
        rY.left = rY.right - scrollSize;

        //if(hasX) rY.bottom -= scrollSize;
        bInY = inRect(rY, x, y);
    }

    if(hasX){
        rX = new RECT();
        rX.bottom = e.offset().top + e.height();
        rX.left = e.offset().left;
        rX.top = rX.bottom - scrollSize;
        rX.right = rX.left + e.width();

        //if(hasY) rX.right -= scrollSize;
        bInX = inRect(rX, x, y);
    }

    return bInX || bInY;
}

Are all scrollbar sizes uniform? E.g in Firefox and IE it's 18px.
Assuming there are no customized scrollbars, is there any extra padding or sizes in some browsers?

These functions all perform as intended (from what I can discern).

Making custom events was a bit trickier, but I got it to work somewhat. The only problem is that if the element clicked has a mousedown/up event attached to it, that will be triggered as well.

I can't seem to stop the other events from triggering while simultaneously triggering, what I call, the mousedownScroll/mouseupScroll events.

$.fn.mousedownScroll = function(fn, data){
    if(typeof fn == "undefined" && typeof data == "undefined"){
        $(this).trigger("mousedownScroll");
        return;
    }

    $(this).on("mousedownScroll", data, fn);
};

$.fn.mouseupScroll = function(fn, data){
    if(typeof fn == "undefined" && typeof data == "undefined"){
        $(this).trigger("mouseupScroll");
        return;
    }

    $(this).on("mouseupScroll", data, fn);
};

$(document).on("mousedown", function(e){
    if(inScrollRange(e)){
        $(e.target).trigger("mousedownScroll");
    }
});

$(document).on("mouseup", function(e){
    if(inScrollRange(e)){
        $(e.target).trigger("mouseupScroll");
    }
});

$("selector").mousedown(function(e){
    console.log("Clicked content."); //Fired when clicking scroller as well
});

$("selector").mousedownScroll(function(e){
    console.log("Clicked scroller.");
});

How do I stop the other "click" events from triggering?

While I'm asking, please feel free to optimize the code as much as possible.

Here's a JSFiddle to mess around with.

The reason I'm making this is because of a bigger plugin I'm developing. It's got a custom context menu that is showing up when I right click one of the scrollers. I don't want that. So I thought I should make an event that checks for scroll clicks (mouseup/downs) and then prevent the context menu from being displayed. In order to do that though, I need the scroll click to come before the normal click, and also, if possible, stop the normal clicks from firing.

I'm just thinking out loud here but maybe there's a way to get all the functions that are bound to the element and then switch the order in which they were added? I know that functions are executed in the order they were added (1st added 1st called), so, if I could tap into that process, perhaps the whole "registering" of the event to JQuery could just be inserted before the click events.

^{¹ can only use mousedown/mouseup because click doesn't trigger when clicking on a scrollbar. If this is false, please provide a working example/code}

标签： events scrollbar jquery

10条回答

Anthone

2楼-- · 2019-01-03 17:59

Ensure that the content of your scollarea completely [over]fills the parent div.

Then, you can differentiate between clicks on your content and clicks on your container.

html:

<div class='test container'><div class='test content'></div></div>
<div id="results">please click</div>

css:

#results {
  position: absolute;
  top: 110px;
  left: 10px;
}

.test {
  position: absolute;
  left: 0;
  top: 0;
  width: 100px;
  height: 100px;
  background-color: green;
}

.container {
  overflow: scroll;
}

.content {
  background-color: red;
}

js:

function log( _l ) {
  $("#results").html( _l );
}

$('.content').on( 'mousedown', function( e ) {
  log( "content-click" );
  e.stopPropagation();
});

$('.container').on( 'mousedown', function( e ) {
  var pageX = e.pageX;
  var pageY = e.pageY;
  log( "scrollbar-click" );
});

http://codepen.io/jedierikb/pen/JqaCb

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We Are One

3楼-- · 2019-01-03 18:03

Just detect if element.offsetLeft + element.scrollWidth < event.clientX under element.onmousedown. An element's scrollWidth does not include the width of the scrollbar. It only includes that of the inner content. If you want to also detect with a horizontal scrollbar, the same can be applied on that scale using height and Y position instead of width and X position.

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太酷不给撩

4楼-- · 2019-01-03 18:05

Solved:

A shortest scrollbar click detection I could come up with, tested on IE, Firefox, Chrome.

var clickedOnScrollbar = function(mouseX){
  if( $(window).outerWidth() <= mouseX ){
    return true;
  }
}

$(document).mousedown(function(e){
  if( clickedOnScrollbar(e.clientX) ){
    alert("clicked on scrollbar");
  }
});

Working example: https://jsfiddle.net/s6mho19z/

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爱情/是我丢掉的垃圾

5楼-- · 2019-01-03 18:11

I'll submit my own answer and accept Alexander's answer, because it made it work perfectly, and upvote Samuel's answer, because it correctly calculates the scrollbar width, which is what I needed as well.

That being said, I decided to make two independent events instead of trying to overwrite/override JQuery's mousedown event.

This gave me the flexibility I needed without messing with JQuery's own events, and was quite easy to do.

mousedownScroll
mousedownContent

Below are the two implementations using Alexanders, and my own. Both work as I originally intended them to, but the former is probably the best.

Here's a JSFiddle that implements Alexander's answer + Samuel's answer.

$.fn.hasScroll = function(axis){
    var overflow = this.css("overflow"),
        overflowAxis;

    if(typeof axis == "undefined" || axis == "y") overflowAxis = this.css("overflow-y");
    else overflowAxis = this.css("overflow-x");

    var bShouldScroll = this.get(0).scrollHeight > this.innerHeight();

    var bAllowedScroll = (overflow == "auto" || overflow == "visible") ||
                         (overflowAxis == "auto" || overflowAxis == "visible");

    var bOverrideScroll = overflow == "scroll" || overflowAxis == "scroll";

    return (bShouldScroll && bAllowedScroll) || bOverrideScroll;
};

$.fn.mousedown = function(data, fn) {
    if ( fn == null ) {
        fn = data;
        data = null;
    }    
    var o = fn;
    fn = function(e){
        if(!inScrollRange(e)) {
            return o.apply(this, arguments);
        }
        return;
    };
    if ( arguments.length > 0 ) {
        return this.bind( "mousedown", data, fn );
    } 
    return this.trigger( "mousedown" );
};

$.fn.mouseup = function(data, fn) {
    if ( fn == null ) {
        fn = data;
        data = null;
    }    
    var o = fn;
    fn = function(e){
        if(!inScrollRange(e)) {
            return o.apply(this, arguments);
        }
        return;
    };
    if ( arguments.length > 0 ) {
        return this.bind( "mouseup", data, fn );
    } 
    return this.trigger( "mouseup" );
};

$.fn.mousedownScroll = function(data, fn) {
    if ( fn == null ) {
        fn = data;
        data = null;
    }    
    var o = fn;
    fn = function(e){
        if(inScrollRange(e)) {
            e.type = "mousedownscroll";
            return o.apply(this, arguments);
        }
        return;
    };
    if ( arguments.length > 0 ) {
        return this.bind( "mousedown", data, fn );
    } 
    return this.trigger( "mousedown" );
};

$.fn.mouseupScroll = function(data, fn) {
    if ( fn == null ) {
        fn = data;
        data = null;
    }    
    var o = fn;
    fn = function(e){
        if(inScrollRange(e)) {
            e.type = "mouseupscroll";
            return o.apply(this, arguments);
        }
        return;
    };
    if ( arguments.length > 0 ) {
        return this.bind( "mouseup", data, fn );
    } 
    return this.trigger( "mouseup" );
};

var RECT = function(){
    this.top = 0;
    this.left = 0;
    this.bottom = 0;
    this.right = 0;
}

function inRect(rect, x, y){
    return (y >= rect.top && y <= rect.bottom) &&
           (x >= rect.left && x <= rect.right)
}


var scrollSize = measureScrollWidth();

function inScrollRange(event){
    var x = event.pageX,
        y = event.pageY,
        e = $(event.target),
        hasY = e.hasScroll(),
        hasX = e.hasScroll("x"),
        rX = null,
        rY = null,
        bInX = false,
        bInY = false

    if(hasY){ 
        rY = new RECT();
        rY.top = e.offset().top;
        rY.right = e.offset().left + e.width();
        rY.bottom = rY.top +e.height();
        rY.left = rY.right - scrollSize;

        //if(hasX) rY.bottom -= scrollSize;
        bInY = inRect(rY, x, y);
    }

    if(hasX){
        rX = new RECT();
        rX.bottom = e.offset().top + e.height();
        rX.left = e.offset().left;
        rX.top = rX.bottom - scrollSize;
        rX.right = rX.left + e.width();

        //if(hasY) rX.right -= scrollSize;
        bInX = inRect(rX, x, y);
    }

    return bInX || bInY;
}

$(document).on("mousedown", function(e){
    //Determine if has scrollbar(s)
    if(inScrollRange(e)){
        $(e.target).trigger("mousedownScroll");
    }
});

$(document).on("mouseup", function(e){
    if(inScrollRange(e)){
        $(e.target).trigger("mouseupScroll");
    }
});
});

function measureScrollWidth() {
    var scrollBarMeasure = $('<div />');
    $('body').append(scrollBarMeasure);
    scrollBarMeasure.width(50).height(50)
        .css({
            overflow: 'scroll',
            visibility: 'hidden',
            position: 'absolute'
        });

    var scrollBarMeasureContent = $('<div />').height(1);
    scrollBarMeasure.append(scrollBarMeasureContent);

    var insideWidth = scrollBarMeasureContent.width();
    var outsideWitdh = scrollBarMeasure.width();
    scrollBarMeasure.remove();

    return outsideWitdh - insideWidth;
};

Here's a JSFiddle of what I decided to do instead.

$.fn.hasScroll = function(axis){
    var overflow = this.css("overflow"),
        overflowAxis,
        bShouldScroll,
        bAllowedScroll,
        bOverrideScroll;

    if(typeof axis == "undefined" || axis == "y") overflowAxis = this.css("overflow-y");
    else overflowAxis = this.css("overflow-x");

    bShouldScroll = this.get(0).scrollHeight > this.innerHeight();

    bAllowedScroll = (overflow == "auto" || overflow == "visible") ||
        (overflowAxis == "auto" || overflowAxis == "visible");

    bOverrideScroll = overflow == "scroll" || overflowAxis == "scroll";

    return (bShouldScroll && bAllowedScroll) || bOverrideScroll;
};

$.fn.mousedownScroll = function(fn, data){
    var ev_mds = function(e){
        if(inScrollRange(e)) fn.call(data, e);
    }
    $(this).on("mousedown", ev_mds);
    return ev_mds;
};

$.fn.mouseupScroll = function(fn, data){
    var ev_mus = function(e){
        if(inScrollRange(e)) fn.call(data, e);
    }
    $(this).on("mouseup", ev_mus);
    return ev_mus;
};

$.fn.mousedownContent = function(fn, data){
    var ev_mdc = function(e){
        if(!inScrollRange(e)) fn.call(data, e);
    }

    $(this).on("mousedown", ev_mdc);

    return ev_mdc;
};

$.fn.mouseupContent = function(fn, data){
    var ev_muc = function(e){
        if(!inScrollRange(e)) fn.call(data, e);
    }
    $(this).on("mouseup", ev_muc);
    return ev_muc;
};

var RECT = function(){
    this.top = 0;
    this.left = 0;
    this.bottom = 0;
    this.right = 0;
}

function inRect(rect, x, y){
    return (y >= rect.top && y <= rect.bottom) &&
        (x >= rect.left && x <= rect.right)
}

var scrollSize = measureScrollWidth();

function inScrollRange(event){
    var x = event.pageX,
        y = event.pageY,
        e = $(event.target),
        hasY = e.hasScroll(),
        hasX = e.hasScroll("x"),
        rX = null,
        rY = null,
        bInX = false,
        bInY = false

    if(hasY){ 
        rY = new RECT();
        rY.top = e.offset().top;
        rY.right = e.offset().left + e.width();
        rY.bottom = rY.top +e.height();
        rY.left = rY.right - scrollSize;

        //if(hasX) rY.bottom -= scrollSize;
        bInY = inRect(rY, x, y);
    }

    if(hasX){
        rX = new RECT();
        rX.bottom = e.offset().top + e.height();
        rX.left = e.offset().left;
        rX.top = rX.bottom - scrollSize;
        rX.right = rX.left + e.width();

        //if(hasY) rX.right -= scrollSize;
        bInX = inRect(rX, x, y);
    }

    return bInX || bInY;
}

function measureScrollWidth() {
    var scrollBarMeasure = $('<div />');
    $('body').append(scrollBarMeasure);
    scrollBarMeasure.width(50).height(50)
        .css({
            overflow: 'scroll',
            visibility: 'hidden',
            position: 'absolute'
        });

    var scrollBarMeasureContent = $('<div />').height(1);
    scrollBarMeasure.append(scrollBarMeasureContent);

    var insideWidth = scrollBarMeasureContent.width();
    var outsideWitdh = scrollBarMeasure.width();
    scrollBarMeasure.remove();

    return outsideWitdh - insideWidth;
};

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