step ctrl

window.$stepCtrl = {
    elementData:{},
    targetContents:{},
    onload:function(){
        var elements = document.getElementsByClassName('laz-steps');
        try{
            for (var i in elements){
                var element = elements[i];
                if (is_element(element)){
                    var key = element.getAttribute("laz-key");
                    var idx = element.getAttribute('laz-step-index');
                    if (!this.elementData[key])
                    {
                        this.elementData[key] = {
                            "index-now":-1,
                            elements:{}
                        };
                    }
                    this.elementData[key]['elements'][parseInt(idx)] = element;
                    if (idx == 0){
                        this.nextStep(key);
                    }
                }
            }
        }catch (e){
            console.warn(e);
        }
    },
    nextStep:function(key){
        try{
            var idx = this.elementData[key]['index-now'];
            if (idx != -1){
                this.elementData[key]['elements'][idx].setAttribute("laz-active","hide");
            }
            idx ++;
            this.elementData[key]['elements'][idx].setAttribute("laz-active","show");
            this.elementData[key]['index-now'] = idx;
        }catch (e){
            console.warn(e);
        }
    },
    lastStep:function(key){
        try{
            var idx = this.elementData[key]['index-now'];
            if (idx != -1){
                this.elementData[key]['elements'][idx].setAttribute("laz-active","hide");
            }
            if (idx > 0){
                idx --;
                this.elementData[key]['elements'][idx].setAttribute("laz-active","show");
                this.elementData[key]['index-now'] = idx;
            }
        }catch (e){
            console.warn(e);
        }
    }

};

        <div class="laz-steps" laz-step-index="0" laz-key="register">
            <form method="post" laz-action="" laz-call="step1" onsubmit="return LazFormCheck(this);">
                <div class="std-form-group">
                    <label>邀请人手机号</label>
                    <input type="text"  name="inviter" class="std-form-control"/>
                </div>
                <button type="submit" class="std-btn std-btn-warning">下一步</button>
            </form>
        </div>