Table隔行变色JavaScript

Table隔行变色

function showtable(){
        var color1  = "rgb(234,240,255)";
        var color2  = "rgb(255,255,255)";
        var bgColor = "rgb(255,255,193)";
        var trs = document.getElementById("datatable").getElementsByTagName("tr");
        for (var i=0;i<trs.length-1;i++){
            if (i%2==0) {
                trs[i].style.backgroundColor=color1;
                trs[i].onmouseover = function(){
                    this.style.backgroundColor = bgColor;
                }
                trs[i].onmouseout = function(){
                    this.style.backgroundColor = color1;
                }
            } else {
                trs[i].style.backgroundColor=color2;
                trs[i].onmouseover = function(){
                    this.style.backgroundColor = bgColor;
                }
                trs[i].onmouseout = function(){
                    this.style.backgroundColor = color2;
                }
            }
        }
    }