Vue.js：计算平均值并更新字段答案

【问题标题】：Vue.js: Calculate average and update fieldVue.js：计算平均值并更新字段
【发布时间】：2015-05-28 08:19:13
【问题描述】：

我正在尝试计算不等于零的子成绩的平均值，并将绑定输入设置为新的平均值。

子等级有一个调用 calcAverage() 函数的 v-on 指令。在这我认为你应该更新各自的 avgGrade 值。

HTML：

<div id="container">
    <div class="row" v-repeat="testData">
        <p>Grade avg:
            <!--this should be average of sub grades that aren't 0-->
            <input type="text" v-model="avgGrade" disabled />
            <div v-repeat="vals">Sub grade {{item}}:
                <input type="text" v-model="grade" v-on="change:calcAverage" />
            </div>
        </p>
    </div>
</div>

JS：

var data = [
    {item: 1,avgGrade: 2,vals: [{grade: 2}, {grade: 2}, {grade: 2}]},
    {item: 2,avgGrade: 3,vals: [{grade: 3}, {grade: 3}, {grade: 3}]},
    {item: 3,avgGrade: 4,vals: [{grade: 4}, {grade: 4}, {grade: 4}]}
];
var testVue = new Vue({
    el: '#container',
    data: {
        testData: data
    },
    methods: {
        calcAverage: function (e) {
            //calculate the average of sub grades
            //change Grade avg to show this
        }
    }
});

小提琴：https://jsfiddle.net/ksumarine/bwrvsmpk/

谢谢！

【问题讨论】：

标签： javascript jquery vue.js

【解决方案1】：

您可以将重复项传递给您的change 事件回调函数，就像这样：

HTML

<div id="container">
    <div class="row" v-repeat="testData">
        <p>Grade avg:
            <!--this should be average of sub grades that aren't 0-->
            <input type="text" v-model="avgGrade" disabled />
            <div v-repeat="vals" v-with="subItem: $data">Sub grade {{item}}:
                <input type="text" v-model="grade" v-on="change:calcAverage(subItem)" />
            </div>
        </p>
    </div>
</div>

var data = [
    {item: 1,avgGrade: 2,vals: [{grade: 2}, {grade: 2}, {grade: 2}]},
    {item: 2,avgGrade: 3,vals: [{grade: 3}, {grade: 3}, {grade: 3}]},
    {item: 3,avgGrade: 4,vals: [{grade: 4}, {grade: 4}, {grade: 4}]}
];

var testVue = new Vue({
    el: '#container',
    data: {
        testData: data
    },
    methods: {
        calcAverage: function (subItem) {
            var total = 0,
                length = subItem.vals.length;

            for (var i = 0; i < length; i++) {
                total += parseFloat(subItem.vals[i].grade);
            }

            subItem.avgGrade = total / length;
        }
    }
});

假设你的avgGrade是浮动的，我这里用parseFloat，你可以随意改成parseInt。

这是JSFiddle。

【讨论】：