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Angular $http request

Timing of an $http request


The $http requests require time which varies depending on the server, some may take a few milliseconds, and some may take up to a few seconds. Often the time required to retrieve the data from a request is critical.
Assuming the response value is an array of names, consider the following example:

Incorrect


$scope.names = [];
$http({
 method: 'GET',
 url: '/someURL'
}).then(function successCallback(response) {
 $scope.names = response.data;
 },
 function errorCallback(response) {
 alert(response.status);
 });
alert("The first name is: " + $scope.names[0]);

Accessing $scope.names[0] right below the $http request will often throw an error - this line of code executes before the response is received from the server.

Correct


$scope.names = [];
$scope.$watch('names', function(newVal, oldVal) {
 if(!(newVal.length == 0)) {
 alert("The first name is: " + $scope.names[0]);
 }
});
$http({
 method: 'GET',
 url: '/someURL'
}).then(function successCallback(response) {
 $scope.names = response.data;
 },
 function errorCallback(response) {
 alert(response.status);
 });

Using the $watch service we access the $scope.names array only when the response is received. During initialization, the function is called even though $scope.names was initialized before, therefore checking if the newVal.length is different than 0 is necessary. Be aware - any changes made to $scope.names will trigger the watch function.

Conclusion

In this page (written and validated by ) you learned about AngularJS $http request . What's Next? If you are interested in completing AngularJS tutorial, your next topic will be learning about: AngularJS Using http inside a controller.



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