vue watch div width change - 快车库

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <link href="http://cdn.bootcss.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
    <div class='container-fluid' id="demo">
        <div class="row" style="width:1000px;">
            <div v-resize="changed()" class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
            <div class="col-md-1">.col-md-1</div>
        </div>
        <div class="row">
            <div class="col-md-8">.col-md-8</div>
            <div class="col-md-4">.col-md-4</div>
        </div>
        <div class="row">
            <div class="col-md-4">.col-md-4</div>
            <div class="col-md-4">.col-md-4</div>
            <div class="col-md-4">.col-md-4</div>
        </div>
        <div class="row">
            <div class="col-md-6">.col-md-6</div>
            <div class="col-md-6">.col-md-6</div>
        </div>
    </div>

    <script src="http://apps.bdimg.com/libs/ueditor/1.4.3.1/ueditor.config.js"></script>
    <script src="http://apps.bdimg.com/libs/ueditor/1.4.3.1/ueditor.all.js"></script>
    <script src="http://apps.bdimg.com/libs/ueditor/1.4.3.1/lang/zh-cn/zh-cn.js"></script>
    <script src="http://cdn.bootcss.com/vue/1.0.17/vue.min.js"></script>

    <script type="text/javascript">
        'use strict'

        //http://vuejs.org.cn/guide/custom-directive.html
        Vue.directive('resize', {
            bind: function () {
                this.handler = function () {
                    var width = this.el.offsetWidth

                    if (this.width === width) {

                    }
                    else {
                        console.log(this.width, width)
                        this.width = width
                        this.vm.$get(this.expression)
                    }
                }.bind(this)

                window.addEventListener('resize', this.handler)
            },
            update: function (newValue, oldValue) {

            },
            unbind: function () {
                window.removeEventListener('resize', this.handler)
            }
        })

        var vm = new Vue({
            el: '#demo',
            methods: {
                changed() {
                    console.log('resize')
                },
            }
        })
    </script>
</body>
</html>