通过style属性设置背景图案
<!--html--> <div> change color </div>
/*css*/ #change { border: 1px solid black; width: 200px; height: 200px; text-align: center; line-height: 200px; }
//js change.style.backgroundColor="purple";
在侧边栏设置一个颜色选择器，将change的背景颜色设置为选择的颜色，此时颜色选择器的颜色是使用内联样式的方式添加的。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>css</title> <style> * { margin: 0; padding: 0; } .wrap { width: 220px; height: 200px; position: absolute; top: 300px; left: -172px; } .open-close { height: 45px; width: 48px; background: url("open-close.png") no-repeat; background-size: contain; border: 1px solid grey; border-left: none; position: absolute; top: 0; right: 0; z-index: 2; } .changer { height: 150px; width: 170px; position: absolute; top: 0; left: 0; border: 1px solid grey; text-align: center; padding-top: 8px; } .list > li { display: block; width: 36px; height: 36px; float: left; margin-left: 9%; margin-top: 10%; } #change { border: 1px solid black; width: 200px; height: 200px; text-align: center; line-height: 200px; } </style> </head> <body> <div> <!--html--> <div></div> <div> <span>颜色选择器</span> <ul> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> </div> </div> <div> change color </div> <script> var open = document.getElementById("open"); var wrap = document.getElementById("wrap"); var list = document.getElementById("list"); var change = document.getElementById("change"); var color_change = document.getElementsByTagName("li"); change.style.backgroundColor = "purple"; open.onmouseover = function () { wrap.style.left = 0 + "px"; }; open.onclick = function () { wrap.style.left = -172 + "px"; }; for (var i = 0; i < color_change.length; i++) { color_change[i].id = i; color_change[i].onclick = function () { change.style.backgroundColor = color_change[this.id].style.backgroundColor; } } </script> </body> </html>
问题：
当颜色选择器的颜色是使用嵌入式或者外部引入的方式添加时，javascript的style属性无效，获取不到颜色值。
解决方法：
javascript的style属性只能获取内联样式，对于外部引入样式和嵌入式样式需要用currentStyle属性。但是，currentStyle在Firefox和Chrome下不支持，需要使用如下兼容性代码:
HTMLElement.prototype.__defineGetter__("currentStyle", function () { return this.ownerDocument.defaultView.getComputedStyle(this, null); });
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> * { margin: 0; padding: 0; } .wrap { width: 220px; height: 200px; position: absolute; top: 300px; left: -172px; } .open-close { height: 45px; width: 48px; background: url("open-close.png") no-repeat; background-size: contain; border: 1px solid grey; border-left: none; position: absolute; top: 0; right: 0; z-index: 2; } .changer { height: 150px; width: 170px; position: absolute; top: 0; left: 0; border: 1px solid grey; text-align: center; padding-top: 8px; } .list > li { display: block; width: 36px; height: 36px; float: left; margin-left: 9%; margin-top: 10%; } .color-orange { background-color: orange; } .color-red { background-color: red; } .color-blue { background-color: blue; } .color-blank { background-color: black; } .color-green { background-color: green; } .color-pink { background-color: pink; } #change { border: 1px solid black; width: 200px; height: 200px; text-align: center; line-height: 200px; } </style> </head> <body> <div> <!--html--> <div></div> <div> <span>颜色的选择</span> <ul> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> </div> </div> <div> change color </div> <script> HTMLElement.prototype.__defineGetter__("currentStyle", function () { return this.ownerDocument.defaultView.getComputedStyle(this, null); }); var open = document.getElementById("open"); var wrap = document.getElementById("wrap"); var list = document.getElementById("list"); var change = document.getElementById("change"); var color_change = document.getElementsByTagName("li"); change.style.backgroundColor="purple"; open.onmouseover = function () { wrap.style.left = 0 + "px"; }; open.onclick = function () { wrap.style.left = -172 + "px"; }; for (var i = 0; i < color_change.length; i++) { color_change[i].id = i; color_change[i].onclick = function () { change.style.backgroundColor = color_change[this.id].currentStyle.backgroundColor; } } </script> </body> </html>