There are some times when you might want to dynamically add elements to the page in response to some user action. Maybe you’re writing a form builder app, and users can add chunks of the form one at a time.
In this case, you want the order of the displayed forms to match the order of the button clicks. So if you have 3 buttons (A, B, C) and the user clicks (B, C, A), then you want form B to be added first, then C, then A.
Here’s an example that works this way. Try clicking the buttons.
The controller has an array of form template names. When a button is clicked, the matching form template name is added to an array of displayed forms. An ng-repeat directive loops array over the list of displayed forms, and uses ng-include to render the templates.
The HTML is simple, and for the sake of making it easy to understand, it includes some inline templates. In a real app, you’d probably want to put these in files and integrate them into your build process.
<body ng-app="exampleApp" ng-controller="DynamicFormCtrl as ctrl">
<div>
<button ng-click="ctrl.addForm(0)">Form One</button>
<button ng-click="ctrl.addForm(1)">Form Two</button>
<button ng-click="ctrl.addForm(2)">Form Three</button>
</div>
<div ng-repeat="form in ctrl.displayedForms track by $index">
<ng-include src="form"></ng-include>
</div>
<script type="text/ng-template" id="form1.tpl.html">
<label>
Form one is an input: <input type="text" />
</label>
</script>
<script type="text/ng-template" id="form2.tpl.html">
<label>
Form two gives you choices: <input type="radio"/> <input type="radio"/>
</label>
</script>
<script type="text/ng-template" id="form3.tpl.html">
<button>Form three is a button</button>
</script>
</body>
The JS code is very simple. All it needs to do is add items to an array when the user clicks buttons.
angular.module("exampleApp", [])
.controller("DynamicFormCtrl", function() {
var ctrl = this;
var forms = [
"form1.tpl.html",
"form2.tpl.html",
"form3.tpl.html",
];
ctrl.displayedForms = [];
ctrl.addForm = function(formIndex) {
ctrl.displayedForms.push(forms[formIndex]);
}
});
One important thing to notice with this approach is that you need to use the “track by” syntax (in this case, track by $index) if you want to allow repeat values - otherwise you’ll get an error saying “Duplicates in a repeater are not allowed.”
If you don’t want to allow repeats, just check before adding each form to the displayedForms array.
Dynamically Add Elements to the Page With Angular's ng-repeat and ng-include was originally published by Dave Ceddia at Angularity on August 03, 2015.
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