我是Javascript / jQuery / CSS / HTML的初学者。谢谢你的阅读!
我的代码使用XML请求逐行读取多个文本文件到Javascript中。每行保存矩形的坐标和矩形的相关叠加文本。如下面的代码片段所示,我为文本文件的每一行创建了一个区域元素(一个矩形)。然后我将每个区域元素附加到地图'demo'。然后我将所有这些区域元素转换为div CSS元素,这样我就可以使用jQuery .show()方法显示和隐藏矩形。这样做的问题是,当我使用.show()时,有这么多的矩形会有明显的滞后。
所以我一直在尝试实现CSS悬停选择器以更加即时地显示矩形并且一直停留在语法上。我所有的矩形CSS div(见下面的代码)都是类“area”。我在HTML头中尝试过这样的事情:
<style>
.area:hover {
background: blue;
}
</style>
但没有结果。我想我必须以某种方式在jQuery中执行'hover'动作,但不知道如何做到这一点。
这是一个jsfiddle,描述了我想要实现的目标:https://jsfiddle.net/d1amzfLx/4/
这是一个代码片段,它在我开始多个文本文件的for循环之后开始,并开始在矩形中作为区域元素读取,并在每个矩形对应于鼠标悬停的像素(及其覆盖ID)之后结束)显示。
// get text contents by looping over i text files
j=20000*i + 50000;
var coords = xhr[i].responseText.split("\n");
coords = coords.filter(Boolean) //prevents extra rect with 0 coords
coords.forEach(function(coord) {
var area = document.createElement("area");
area.id = "r"+j;
area.shape = "rect";
area.coords = coord.substring(10,coord.length).trim().replace(/ +/g,","); // replaces spaces in txt file with commas
area.href = "#";
area.alt = "r"+j;
// create overlay with first term in string
var div = document.createElement("div");
div.className = "cont";
div.id ="overlayr"+j;
div.innerHTML = coord.substring(0,10);
div.style.display = "none";
//increase j
j++;
document.getElementById("demo").appendChild(area);
document.getElementById("demo").appendChild(div);
//all rectangles and their overlay texts are appended to the map 'demo'
});
//display rectangles and overlay ids by mousing over
if( $('#demo').length >0 ) {
var hoveredElements = [];
var elementPositions = [];
$('#demo area').each(function() {
var offset = this.coords;
var coordarray = offset.split(",");
var l = coordarray[0];
var t = coordarray[1];
var r = coordarray[2];
var b = coordarray[3];
var ident = this.id;
var w = r - l;
var h = b - t;
var elementDiv = $('<div class="area"></div>')
.css({position: 'absolute', left: l + 'px', top: t + 'px', border: 'solid', borderColor: 'green' }).
width(w).height(h);
$("body").append(elementDiv);
elementDiv.hide();
//console.log("Top =" + top + ",Left =" + left + ",Bottom =" + bottom + ",Right =" + right);
elementPositions.push({
element: elementDiv,
top: t,
bottom: b,
left: l,
right: r,
id: ident,
});
}); //end of demo area
//console.log("elementPositions.length=" + elementPositions.length);
$("body").mousemove(function(e) {
//console.log("clearing hovered elements");
hoveredElements.forEach( function(item) {
item.overlay.hide();
item.element.hide();
});
hoveredElements = [];
var xPosition = e.pageX;
var yPosition = e.pageY;
//console.log(xPosition,yPosition);
for (var ie = 0; ie < elementPositions.length; ie++) {
var id = elementPositions[ie].id;
if (xPosition >= elementPositions[ie].left &&
xPosition <= elementPositions[ie].right &&
yPosition >= elementPositions[ie].top &&
yPosition <= elementPositions[ie].bottom) {
// The mouse is within the element's boundaries
//console.log("Element" + ie + "hit");
hoveredElements.push({
overlay: $('#overlay' + id),
element: elementPositions[ie].element,
});
}
} //end of for loop over all elements
hoveredElements.forEach( function(item) {
item.overlay.show();
//item.element.show(); this command shows the CSS div rectangles, but they take too long to load!
});//end of for loop over all hovered elements
}); //end of mousemove function
}; //end of if demo
答案 0 :(得分:1)
这会将课程.area
的所有div更改为background-color:blue;
$(document).on("mouseenter", ".area", function() {
$( '.area' ).css('background-color','blue');
});
这是你的老鼠离开的时候。默认情况下,颜色是指在更改为蓝色之前div所具有的背景颜色
$(document).on("mouseleave", ".area", function() {
$( '.area' ).css('background-color','defaultColor');
});
另外,为了获得更好的性能,您应该使用.area
父ID或类