使用 ngChange 更新模型时遇到问题答案

【问题标题】：Having trouble using ngChange to update model使用 ngChange 更新模型时遇到问题
【发布时间】：2015-08-18 23:30:22
【问题描述】：

我刚开始学习 Angular 的基础知识。我正在尝试制作年薪转换器，只是为了好玩。当用户更改年度模型时，我的每月 ng-model 更新有困难。这些字段是输入标签。这是代码

    <!doctype html>
<html ng-app="salaryApp">
    <head>
        <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css" rel="stylesheet">
    </head>
    <body>
        <div class="container" ng-controller="converter">
            <h1>Salary converter</h1>
            <div class="form-group">
                <label>Annual Salary</label>
                <input type="number" class="form-control" placeholder="0" ng-model="yearly" ng-change="reCalculate()" >
                <br>
                <label>Monthly Salary</label>
                <input type="number" class="form-control" placeholder="0" ng-model="monthly" disabled>
            </div>

        </div>
        <!--<div ng-controller="converter">
            Write some text in textbox:
            <input type="text">

            <h1>Hello {{ yearly }}</h1>
            <h1>Hello {{ monthly }}</h1>
        </div>-->
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js"></script>
        <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.15/angular.min.js"></script>
        <!--<script src="salaryConverter.js"></script>-->
        <script type="text/javascript">
            var app = angular.module('salaryApp', []);



app.controller('converter', function($scope) {
  $scope.yearly = 80000;
  console.log("log1");
  $scope.monthly = $scope.yearly / 12;
  console.log("log2");

    function reCalculate() {
        console.log("function was run");
        return $scope.yearly /12.00;

  }

});
</script>

    </body>
</html>

这里是 plnkr http://plnkr.co/edit/26y0JRR7iVcrLOBlm7D2?p=preview

【问题讨论】：

标签： javascript angularjs angular-ngmodel angularjs-ng-change ng-controller

【解决方案1】：

app.controller('converter', function($scope) {
  $scope.yearly = 80000;
  console.log("log1");
  $scope.monthly = $scope.yearly / 12;
  console.log("log2");

    $scope.reCalculate = function () {
        console.log("function was run");
        $scope.monthly = $scope.yearly / 12;

  }

});

这是你的plunker 工作

【讨论】：

【解决方案2】：

您需要将 reCalculate 方法添加到您的范围：

app.controller('converter', function($scope) {
  $scope.yearly = 80000;
  $scope.reCalculate = reCalculate; <--- THIS LINE
  console.log("log1");
  $scope.monthly = $scope.yearly / 12;
  console.log("log2");

    function reCalculate() {
        console.log("function was run");
        return $scope.yearly /12.00;

  }

});

你也可以直接添加：

$scope.reCalculate = function()...

但我建议遵循一些关于如何编写控制器的样式指南： https://github.com/johnpapa/angular-styleguide

【讨论】：

【解决方案3】：

将函数定义为$scope，以便从视图中调用并将值分配给monthly，而不是返回。

$scope.reCalculate = function () {
    console.log("function was run");
    $scope.monthly = $scope.yearly / 12.00;
}

DEMO

【讨论】：

【解决方案4】：

您需要将其用作scope 属性。这里：

function reCalculate() {
        console.log("function was run");
        return $scope.yearly /12.00;

  }

应该是

  $scope.reCalculate = function () {
        console.log("function was run");
        $scope.monthly=$scope.yearly /12.00;//Don't return, you neet to assign

  }

【讨论】：

谢谢泽！太简单！我阅读了很多次文档，但错过了具体细节。
@squid267 NP。很高兴帮助:)