我的代码有两段 if 判断是重复的，请问怎么写能简化代码？

Question

if  (num==00){}  if (num==01){}  ..................

这块有两段 if 判断是重复的，能不能给封装起来？或者怎么写能简化代码？

/*向右按钮点击切换----开始*/
    var prev_num = null;
    var ibm_carousel_next = document.getElementsByClassName('ibm-carousel-next')[0];
    ibm_carousel_next.onclick = function() {
        var slick_dots = document.getElementsByClassName('slick-dots')[0];
        var slick_dots_li = slick_dots.getElementsByTagName('li');
        for (var i = 0; i < slick_dots_li.length; i++) {
            if (slick_dots_li[i].getAttribute('class') == 'slick-active') {
                prev_num = slick_dots_li[i].id;
                console.log(prev_num);
                var myString = prev_num;
                var num = myString.substring(11, 13);
                console.log(num);
                if (num == 00) {
                    var h3_description = document.getElementById('h3_description');
                    var p_description_1 = document.getElementById('p_description_1');
                    var p_description_2 = document.getElementById('p_description_2');
                    h3_description.innerHTML='';
                    p_description_1.innerHTML='Watson is a cognitive system that understands, reasons and learns. Marchesa is an iconic high fashion brand that inspires, empowers and creates. See how they worked together to outthink the limits of fashion.';
                    p_description_2.innerHTML='';
                    var thumbnail = document.getElementsByClassName('thumbnail');
                    for (var i = 0; i < thumbnail.length; i++) {
                        thumbnail[0].src = "./images/thumbnail_0.jpg";
                        thumbnail[1].src = "./images/thumbnail_1.jpg";
                        thumbnail[2].src = "./images/thumbnail_2.jpg";
                    };
                }
                if (num == 01) {
                    var h3_description = document.getElementById('h3_description');
                    var p_description_1 = document.getElementById('p_description_1');
                    var p_description_2 = document.getElementById('p_description_2');
                    h3_description.innerHTML='Man-and-Machine Mix-and-Match';
                    p_description_1.innerHTML='How can designers keep materials exciting? IBM Watson developer partner <a target="_blank" href="http://www.inno-360.com/">Inno360</a> used cognitive APIs to help IBM material scientist Victoria Piunova expand her expertise. Watson read over 40,000 sources and helped Marchesa discover materials to bring their fabrics to life.';
                    p_description_2.innerHTML='';
                    var thumbnail = document.getElementsByClassName('thumbnail');
                    for (var i = 0; i < thumbnail.length; i++) {
                        thumbnail[0].src = "./images/thumbnail_1.jpg";
                        thumbnail[1].src = "./images/thumbnail_2.jpg";
                        thumbnail[2].src = "./images/thumbnail_3.jpg";
                    };
                }
            }
        }
    };
    /*向右按钮点击切换----结束*/
    /*向左按钮点击切换----开始*/
    var next_num = null;
    var ibm_carousel_prev = document.getElementsByClassName('ibm-carousel-prev')[0];
    ibm_carousel_prev.onclick = function() {
        var slick_dots = document.getElementsByClassName('slick-dots')[0];
        var slick_dots_li = slick_dots.getElementsByTagName('li');
        for (var i = 0; i < slick_dots_li.length; i++) {
            if (slick_dots_li[i].getAttribute('class') == 'slick-active') {
                next_num = slick_dots_li[i].id;
                console.log(next_num);
                var myString = next_num;
                var num = myString.substring(11, 13);
                console.log(num);
                if (num == 00) {
                    var h3_description = document.getElementById('h3_description');
                    var p_description_1 = document.getElementById('p_description_1');
                    var p_description_2 = document.getElementById('p_description_2');
                    h3_description.innerHTML='';
                    p_description_1.innerHTML='Watson is a cognitive system that understands, reasons and learns. Marchesa is an iconic high fashion brand that inspires, empowers and creates. See how they worked together to outthink the limits of fashion.';
                    p_description_2.innerHTML='';
                    var thumbnail = document.getElementsByClassName('thumbnail');
                    for (var i = 0; i < thumbnail.length; i++) {
                        thumbnail[0].src = "./images/thumbnail_0.jpg";
                        thumbnail[1].src = "./images/thumbnail_1.jpg";
                        thumbnail[2].src = "./images/thumbnail_2.jpg";
                    };
                }
                if (num == 01) {
                    var h3_description = document.getElementById('h3_description');
                    var p_description_1 = document.getElementById('p_description_1');
                    var p_description_2 = document.getElementById('p_description_2');
                    h3_description.innerHTML='Man-and-Machine Mix-and-Match';
                    p_description_1.innerHTML='How can designers keep materials exciting? IBM Watson developer partner <a target="_blank" href="http://www.inno-360.com/">Inno360</a> used cognitive APIs to help IBM material scientist Victoria Piunova expand her expertise. Watson read over 40,000 sources and helped Marchesa discover materials to bring their fabrics to life.';
                    p_description_2.innerHTML='';
                    var thumbnail = document.getElementsByClassName('thumbnail');
                    for (var i = 0; i < thumbnail.length; i++) {
                        thumbnail[0].src = "./images/thumbnail_1.jpg";
                        thumbnail[1].src = "./images/thumbnail_2.jpg";
                        thumbnail[2].src = "./images/thumbnail_3.jpg";
                    };
                }
            }
        }
    }