js实现点击一图标显示另一图标问题,求高手解决,感激感激

    
    
    
        .head_icon {
            height: 30px;
            margin-top: 15px;
        }

        #head_right {
            width: 51px;
            height: 100%;
            background: url(../images/phone_head_right_bg.jpg) no-repeat;
            float: right;
        }
    
    
        function changeicon(plus, subtract) {
            document.getElementById(plus).style.display = "block";
            document.getElementById(subtract).style.display = "none";
        }