Vue 定时执行函数

var app = new Vue({
        el: '#app',
        data: {
            count: ,
        },
        filters: {

        },
        mounted: function () {
            this.$nextTick(function () {
                setInterval(this.timer, );
            })
        },
        methods: {
         timer: function () {
                if (this.count > ) {
                    this.count++;
                }
            }
        },
        watch: {

        },
        computed: {

        }
    });