JQuery: 如何创建一个简单的覆盖？

如何在没有 UI 的情况下在 jQuery 中创建一个真正基本的覆盖？

什么是轻量级插件？

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小开

If you're already using jquery, I don't see why you wouldn't also be able to use a lightweight overlay plugin. Other people have already written some nice ones in jquery, so why re-invent the wheel?

小开

By overlay do you mean content that overlaps/covers the rest of the page? In HTML, you could do this by using a div that uses absolute or fixed positioning. If it needed to be generated dynamically, jQuery could simply generate a div with the position style set appropriately.

小开

What do you intend to do with the overlay? If it's static, say, a simple box overlapping some content, just use absolute positioning with CSS. If it's dynamic (I believe this is called a lightbox), you can write some CSS-modifying jQuery code to show/hide the overlay on-demand.

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最佳答案

An overlay is, simply put, a div that stays fixed on the screen (no matter if you scroll) and has some sort of opacity.

This will be your CSS for cross browser opacity of 0.5:

#overlay {
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: #000;
filter:alpha(opacity=50);
-moz-opacity:0.5;
-khtml-opacity: 0.5;
opacity: 0.5;
z-index: 10000;
}

This will be your jQuery code (no UI needed). You're just going to create a new element with the ID #overlay. Creating and destroying the DIV should be all you need.

var overlay = jQuery('<div id="overlay"> </div>');
overlay.appendTo(document.body)

For performance reasons you might wanna have the DIV hidden and setting the display to block and none as you need it or not.

Hope it helps!

Edit: As @Vitaly so well put it, be sure to check your DocType. Read more on the comments on his findings..

小开

Here's a fully encapsulated version which adds an overlay (including a share button) to any IMG element where data-photo-overlay='true.

http://jsfiddle.net/wloescher/7y6UX/19/

HTML

<img id="my-photo-id" src="http://cdn.sstatic.net/stackexchange/img/logos/so/so-logo.png" alt="Photo" data-photo-overlay="true" />

CSS

#photoOverlay {
background: #ccc;
background: rgba(0, 0, 0, .5);
display: none;
height: 50px;
left: 0;
position: absolute;
text-align: center;
top: 0;
width: 50px;
z-index: 1000;
}


#photoOverlayShare {
background: #fff;
border: solid 3px #ccc;
color: #ff6a00;
cursor: pointer;
display: inline-block;
font-size: 14px;
margin-left: auto;
margin: 15px;
padding: 5px;
position: absolute;
left: calc(100% - 100px);
text-transform: uppercase;
width: 50px;
}

JavaScript

(function () {
// Add photo overlay hover behavior to selected images
$("img[data-photo-overlay='true']").mouseenter(showPhotoOverlay);


// Create photo overlay elements
var _isPhotoOverlayDisplayed = false;
var _photoId;
var _photoOverlay = $("<div id='photoOverlay'></div>");
var _photoOverlayShareButton = $("<div id='photoOverlayShare'>Share</div>");


// Add photo overlay events
_photoOverlay.mouseleave(hidePhotoOverlay);
_photoOverlayShareButton.click(sharePhoto);


// Add photo overlay elements to document
_photoOverlay.append(_photoOverlayShareButton);
_photoOverlay.appendTo(document.body);


// Show photo overlay
function showPhotoOverlay(e) {
// Get sender
var sender = $(e.target || e.srcElement);


// Check to see if overlay is already displayed
if (!_isPhotoOverlayDisplayed) {
// Set overlay properties based on sender
_photoOverlay.width(sender.width());
_photoOverlay.height(sender.height());


// Position overlay on top of photo
if (sender[0].x) {
_photoOverlay.css("left", sender[0].x + "px");
_photoOverlay.css("top", sender[0].y) + "px";
}
else {
// Handle IE incompatibility
_photoOverlay.css("left", sender.offset().left);
_photoOverlay.css("top", sender.offset().top);
}


// Get photo Id
_photoId = sender.attr("id");


// Show overlay
_photoOverlay.animate({ opacity: "toggle" });
_isPhotoOverlayDisplayed = true;
}
}


// Hide photo overlay
function hidePhotoOverlay(e) {
if (_isPhotoOverlayDisplayed) {
_photoOverlay.animate({ opacity: "toggle" });
_isPhotoOverlayDisplayed = false;
}
}


// Share photo
function sharePhoto() {
alert("TODO: Share photo. [PhotoId = " + _photoId + "]");
}
}
)();
小开

Here is a simple javascript only solution

function displayOverlay(text) {
$("<table id='overlay'><tbody><tr><td>" + text + "</td></tr></tbody></table>").css({
"position": "fixed",
"top": 0,
"left": 0,
"width": "100%",
"height": "100%",
"background-color": "rgba(0,0,0,.5)",
"z-index": 10000,
"vertical-align": "middle",
"text-align": "center",
"color": "#fff",
"font-size": "30px",
"font-weight": "bold",
"cursor": "wait"
}).appendTo("body");
}


function removeOverlay() {
$("#overlay").remove();
}

Demo:

http://jsfiddle.net/UziTech/9g0pko97/

Gist:

https://gist.github.com/UziTech/7edcaef02afa9734e8f2

小开

Please check this jQuery plugin,

blockUI

with this you can overlay all the page or elements, works great for me,

Examples: Block a div: $('div.test').block({ message: null });

Block the page: $.blockUI({ message: '<h1><img src="busy.gif" /> Just a moment...</h1>' }); Hope that help someone

Greetings


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