过滤器

$filter 1

HTML

<div ng-app="MyApp">
    <div ng-controller="MyController">
        <input ng-model="beforeFilter" type="text">
        <div ng-bind="afterFilter"></div>
        <div>{{"hello" | nUpperFilter:1}}</div>
    </div>
</div>

JavaScript

angular.module("MyApp", [])
.filter("nUpperFilter",function(){
    return function(input, n){
        if(isNaN(input)){
            var output = [];
            var index = n - 1 || 0;
            var indexChar =  input[index].toUpperCase();
            for(var i = 0; i < input.length; i++){
                if(index == i){
                    output.push(indexChar);
                }
                else{
                    output.push(input[i]);
                }
            }
            return output.join('');
        }
        else{
            return input;
        }
    }
})
    .controller("MyController", function ($scope, $filter) {
    $scope.$watch("beforeFilter", function (newVal) {
       // $scope.afterFilter = $filter("MyFilter")(newVal);
        $scope.console = newVal;
        $scope.afterFilter = $filter("nUpperFilter")(newVal);
    })
});