Custom filter giving "Cannot read property 'slice' of undefined" in AngularJS

angularjs, angularjs-ng-repeat, javascript, pagination

Solution

Your filter needs to check whether or not the input exists:

app.filter('startFrom', function() {
    return function(input, start) {
        if (!input || !input.length) { return; }
        start = +start; //parse to int
        return input.slice(start);
    }
});

Otherwise, the filter function will run and thus call `slice` on `undefined` which doesn't have a property of `slice` like an array or string does.

The reason the filter is called while there is no value is because the filter will run when Angular runs its first `$digest` cycle. You could avoid the error by adding an initial value in the controller, but it's best just to add the `if` statement to the filter.

Here's a demo of both solutions. Notice there are no errors.

Problem

My custom `startFrom` filter is giving me an error. ``` app.filter('startFrom', function() { return function(input, start) { start = +start; //parse to int return input.slice(start); } }); app.controller("PostCtrl", function($scope, $http) { $scope.currentPage = 0; $scope.pageSize = 10; $scope.hidePagination = true; $scope.search = function() { $http.get('someurl').then(sucesscalback,errorcalback); function sucesscalback(response) { $scope.hidePagination = false; console.log("Success:"); console.log(response.data.records); $scope.posts = response.data; $scope.numberOfPages=Math.ceil($scope.posts.records.length/$scope.pageSize); alert($scope.numberOfPages); } function errorcalback(failure) { console.log("Error:"); console.log(failure); } ```

Original source