显示网页盒边框 from: http://www.cnblogs.com/winter-cn/archive/2013/05/11/3072929.html?utm_source=feedly

showbox.js

function randomColor(){
    return "rgb("+Math.floor(Math.random()*255)+","+Math.floor(Math.random()*255)+","+Math.floor(Math.random()*255)+")";
}
function showBoxes(window) {
    var rects = [];
    function getRects(node){
        var range = window.document.createRange();
        range.setStartBefore(node);
        range.setEndAfter(node);
    
        rects.push.apply(rects,range.getClientRects());
  
  
        for(var i = 0; i < node.children.length; i++ )
            getRects(node.children[i]);
    }
    getRects(window.document.documentElement);
  
    window.document.documentElement.style.background = "url('data:image/svg+xml;utf8,<svg xmlns=\"http://www.w3.org/2000/svg\">"+rects.map(function(rect){
        return "<rect x=\""+rect.left+"\" y=\""+rect.top+"\" width=\""+rect.width+"\" height=\""+rect.height+"\" style=\"fill:"+randomColor()+";fill-opacity:0.1;stroke:black;stroke-width:1;\"/>"
    }).join("")+"</svg>') no-repeat";
    window.onresize = function(){ showBoxes(window); };
}