Angular-JS ng-repeat directive is a handy tool to repeat a set of HTML code for a number of times or once per item in a collection of items. ng-repeat is mostly used on arrays and objects.
ng-repeat is similar to a loop that we have in C, C++ or other languages but technically it instantiates a template(normally a set of HTML structures) for each element in a collection that we are accessing. Angular maintains a $index variable as a key to the element which is currently being accessed and a user can also access this variable.
Syntax :
<div ng-repeat="keyName in MyObjectName ">
{{keyName}}
</div>
Here “MyObjectName” is a collection that can be an object or an array and you can access each value inside it using a “keyName”.
Example 1
- Create an app.js file for the app.
var app = angular.module('myApp',[]);
app.controller('MainCtrl', function($scope){
$scope.names = ['Adam','Steve','George','James','Armin'];
console.log($scope.names);
});
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Line 1- Created an app module named “myApp” with no dependencies.
Line 3- Main controller for our application.
Line 4- Array of strings “names”.
- Create index.html page
<!DOCTYPE html>
<html ng-app="myApp">
<head>
<title>Angular ng-repeat</title>
<script> type="text/javascript" src="jquery-3.2.1.min.js">
</script>
<script> type="text/javascript" src="angular.js"></script>
<script> type="text/javascript" src="app.js"></script>
</head>
<body ng-controller="MainCtrl">
<h2>Here is the name list</h2>
<ul>
<li ng-repeat="name in names">
{{name}}
</li>
</ul>
</body>
</html>
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Line 5- Include all the dependencies like jquery, angular-js and app.js file
Line 12- Use ng-repeat directive to get one name from names array at a time and display it.
- Output :
Example 2- app.js file
var app = angular.module('myApp',[]);
app.controller('MainCtrl', function($scope){
$scope.strings= ['Geeks','For','Geeks'];
console.log($scope.strings);
});
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- We have a list of three strings.
index.html
<!DOCTYPE html>
<html ng-app="myApp">
<head>
<title>Angular ng-repeat</title>
<script> type="text/javascript" src="jquery-3.2.1.min.js">
</script>
<script> type="text/javascript" src="angular.js"></script>
<script> type="text/javascript" src="app.js"></script>
</head>
<body ng-controller="MainCtrl">
<h2>Here is the string list</h2>
<ul>
<li ng-repeat="s in strings>
{{name}}
</li>
</ul>
</body>
</html>
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Note-“track by $index” is used here because there are duplicate entries in our list i.e. “Geeks”. Duplicate keys are not allowed because AngularJS uses keys to associate DOM nodes with items. “track by $index”, will cause the items to be keyed by their position in the array instead of their value
- Output :
Applications:
- ng-repeat can be used to iterate through an array which requires less lines of code than the usual javascript method.
- Filters can be used with ng-repeat to create an easy to implement search bar.
References