如何使用angularjs中的ng-repeat迭代JavaScript Maps？

Question

我正在嘗試在搜索時使用ng-repeat angular指令中的JavaScript Maps我發現它可以這樣做：

<ul ng-controller="MyCtrl">
    <li ng-repeat='(key, value) in {"First Name":"John", "Last Name":"Smith"}'>
        <span>Key: {{key}}, value: {{value}}</span>
    </li>
</ul>

但是這只適用於普通的JSON對象，當我以下面的方式創建一個真實的Map時，它不起作用。

我有這個控制器

function MyCtrl($scope) {
    $scope.items = new map();
    $scope.items.set('adam',{'age':10,'fav':'doogie'});
    $scope.items.set('amalie',{'age':12});
}

和這個HTML代碼

<ul>
    <li ng-repeat='(key, value) in items'>
        <span>Key: {{key}}, value: {{value}}</span>
    </li>
</ul>

Answer 1

由於ng-repeat不支持Map迭代，您可以使用fromMap的自定義過濾器，如下所示

 angular.module('app', []).filter('fromMap', function() { return function(input) { var out = {}; input.forEach((v, k) => out[k] = v); return out; }; }).controller('ctrl',function ($scope) { $scope.items = new Map(); $scope.items.set('adam',{'age':10,'fav':'doogie'}); $scope.items.set('amalie',{'age':12}); $scope.logAdamAge = function() { console.log($scope.items.get("adam").age) }; });

 <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script> <div ng-app="app" ng-controller="ctrl"> <div>with Map</div> <ul> <li ng-repeat="(key, value) in items | fromMap"> <div>{{key}}</div> <div ng-repeat="(k, v) in value">{{k}}: <input ng-model="value[k]" /></div> </li> </ul> <pre>{{items | fromMap}}</pre> <button ng-click="logAdamAge()">log Adam age from Map</button> </div>

Answer 2

這是行不通的，因為javascript Map是一個可迭代的對象（你可以只通過條目迭代器循環，每次調用next（））並且不受角度ng-repeat直接支持。

如果你有一個預先存在的代碼，你可以做的是將可迭代對象（map）轉換為普通數組

$scope.itemsToArray = Array.from($scope.items.entries());

這將使您的可迭代對象成為一個數組，此時您可以以標准方式循環

<ul>  
  <li ng-repeat='item in itemsToArray'>
     <span>Key: {{item[0]}}, value: {{item[1]}}</span>
  </li>
</ul>

在這里工作的plnkr

Answer 3

雖然我喜歡Jag的答案，但我已經構建了一個更廣泛的不同實現的片段來實現相同的目標，並且我拿出了大部分ES6箭頭函數和擴展運算符來實現過濾器作為單行： .filter('fromMap', () => mapObject => [...mapObject])

一個設置觀察者，甚至沒有描述觀察者。

以下是如何在Map類對象上實現ng-repeat的方法：

 angular.module('ui.bootstrap.demo', ['ngAnimate', 'ngSanitize', 'ui.bootstrap']); angular.module('ui.bootstrap.demo') .filter('fromMap', () => mapObject => [...mapObject]) .controller('myCtrl', function($scope, $log) { $scope.myMap = new Map([ ['key1', 'value1'], ['key2', 'value2'], ['key3', 'value3'], ['key4', 'value4'], ]); const unsuscribeWatcher1 = $scope.$watch(() => $scope.myMap.size, (newVal, oldVal) => { if (newVal !== oldVal) { //Splicing and pushing keeps the reference to the Array instead of reassigning. $scope.myLoopedMap.splice(0); $scope.myLoopedMap.push(...[...$scope.mySet].filter(k => $scope.myMap.has(k)).map(k => $scope.myMap.get(k))) $scope.myArrFromMap.splice(0); $scope.myArrFromMap.push(...[...$scope.myMap]) } }) const unsuscribeWatcher2 = $scope.$watch(() => $scope.mySet.size, (newVal, oldVal) => { if (newVal !== oldVal) { $scope.myLoopedMap.splice(0); $scope.myLoopedMap.push([...$scope.mySet].filter(k => $scope.myMap.has(k)).map(k => $scope.myMap.get(k))); } }) $scope.mySet = new Set(['key1', 'key3']); $scope.mySet.add('not in the Map') $scope.mySet.add('key7') $scope.myKeys = ['key1', 'key3']; $scope.myArr = [ ['key1', 'value1'], ['key2', 'value2'], ['key3', 'value3'], ['key4', 'value4'], ]; $scope.myArrFromMap = [...$scope.myMap] $scope.myLoopedMap = [...$scope.mySet].filter(k => $scope.myMap.has(k)).map(k => $scope.myMap.get(k)) $scope.myLoopedMap2 = [...$scope.myKeys].reduce((acc, k) => { return $scope.myMap.has(k) ? acc.concat($scope.myMap.get(k)) : acc; }, []) // added to the map later setTimeout(() => { $scope.$apply(() => { // this will be updated as we are watching the Map $scope.myMap.set('key7', 'value7') }) setTimeout(() => { unsuscribeWatcher1(); // this breaks the watching of the Map $scope.$apply(() => { // this will not be updated as the watcher is not working anymore $scope.myMap.set('key8', 'value8') }) }, 3000) }, 3000) });

 <!doctype html> <html ng-app="ui.bootstrap.demo"> <head> <script src="//ajax.googleapis.com/ajax/libs/angularjs/1.6.1/angular.js"></script> <script src="//ajax.googleapis.com/ajax/libs/angularjs/1.6.1/angular-animate.js"></script> <script src="//ajax.googleapis.com/ajax/libs/angularjs/1.6.1/angular-sanitize.js"></script> <script src="//angular-ui.github.io/bootstrap/ui-bootstrap-tpls-2.5.0.js"></script> <script src="example.js"></script> </head> <body> <div ng-controller="myCtrl"> <h3>Some test data data</h3> <div>Get 'key1'======> {{myMap.get('key1')}}</div> <div>Arr ==========> {{myArr}}</div> <div>filtered ======> {{myMap | fromMap}}</div> <div>myArrFromMap=> {{myArrFromMap}}</div> <div>myLoopedMap==> {{myLoopedMap}}</div> <div>myLoopedMap2=> {{myLoopedMap2}}</div> <h3>ng repeat in myLoopedMap</h3> <div ng-repeat="item in myLoopedMap"> Item:`{{item}}` </div> <h3>ng repeat in myArrFromMap</h3> <div ng-repeat="(index, value) in myArrFromMap"> value[0]:`{{value[0]}}`, value[1]:`{{value[1]}}`, index: `{{index}}` </div> </div> </body> </html>

和相應的Plnkr

如何使用angularjs中的ng-repeat迭代JavaScript Maps？

問題描述

3 個解決方案

解決方案1
7 已采納 2017-05-19 15:51:49

解決方案2
1 2017-05-19 15:48:56

解決方案3
0 2017-12-21 14:10:12

如何使用angularjs中的ng-repeat迭代JavaScript Maps？

問題描述

3 個解決方案

解決方案1 7 已采納 2017-05-19 15:51:49

解決方案2 1 2017-05-19 15:48:56

解決方案3 0 2017-12-21 14:10:12

解決方案1
7 已采納 2017-05-19 15:51:49

解決方案2
1 2017-05-19 15:48:56

解決方案3
0 2017-12-21 14:10:12