@ngdoc filter
@name limitTo
@kind function

@description
Creates a new array or string containing only a specified number of elements. The elements
are taken from either the beginning or the end of the source array or string, as specified by
the value and sign (positive or negative) of `limit`.

@param {Array|string} input Source array or string to be limited.
@param {string|number} limit The length of the returned array or string. If the `limit` number
is positive, `limit` number of items from the beginning of the source array/string are copied.
If the number is negative, `limit` number  of items from the end of the source array/string
are copied. The `limit` will be trimmed if it exceeds `array.length`
@returns {Array|string} A new sub-array or substring of length `limit` or less if input array
had less than `limit` elements.

@example
<example module="limitToExample">
<file name="index.html">
<script>
angular.module('limitToExample', [])
.controller('ExampleController', ['$scope', function($scope) {
$scope.numbers = [1,2,3,4,5,6,7,8,9];
$scope.letters = "abcdefghi";
$scope.numLimit = 3;
$scope.letterLimit = 3;
}]);
</script>
<div ng-controller="ExampleController">
Limit {{numbers}} to: <input type="integer" ng-model="numLimit">
<p>Output numbers: {{ numbers | limitTo:numLimit }}</p>
Limit {{letters}} to: <input type="integer" ng-model="letterLimit">
<p>Output letters: {{ letters | limitTo:letterLimit }}</p>
</div>
</file>
<file name="protractor.js" type="protractor">
var numLimitInput = element(by.model('numLimit'));
var letterLimitInput = element(by.model('letterLimit'));
var limitedNumbers = element(by.binding('numbers | limitTo:numLimit'));
var limitedLetters = element(by.binding('letters | limitTo:letterLimit'));

it('should limit the number array to first three items', function() {
expect(numLimitInput.getAttribute('value')).toBe('3');
expect(letterLimitInput.getAttribute('value')).toBe('3');
expect(limitedNumbers.getText()).toEqual('Output numbers: [1,2,3]');
expect(limitedLetters.getText()).toEqual('Output letters: abc');
});

it('should update the output when -3 is entered', function() {
numLimitInput.clear();
numLimitInput.sendKeys('-3');
letterLimitInput.clear();
letterLimitInput.sendKeys('-3');
expect(limitedNumbers.getText()).toEqual('Output numbers: [7,8,9]');
expect(limitedLetters.getText()).toEqual('Output letters: ghi');
});

it('should not exceed the maximum size of input array', function() {
numLimitInput.clear();
numLimitInput.sendKeys('100');
letterLimitInput.clear();
letterLimitInput.sendKeys('100');
expect(limitedNumbers.getText()).toEqual('Output numbers: [1,2,3,4,5,6,7,8,9]');
expect(limitedLetters.getText()).toEqual('Output letters: abcdefghi');
});
</file>
</example>
function limitToFilter(){
  return function(input, limit) {
    if (!isArray(input) && !isString(input)) return input;

    if (Math.abs(Number(limit)) === Infinity) {
      limit = Number(limit);
    } else {
      limit = int(limit);
    }

    if (isString(input)) {
      //NaN check on limit
      if (limit) {
        return limit >= 0 ? input.slice(0, limit) : input.slice(limit, input.length);
      } else {
        return "";
      }
    }

    var out = [],
      i, n;

    // if abs(limit) exceeds maximum length, trim it
    if (limit > input.length)
      limit = input.length;
    else if (limit < -input.length)
      limit = -input.length;

    if (limit > 0) {
      i = 0;
      n = limit;
    } else {
      i = input.length + limit;
      n = input.length;
    }

    for (; i<n; i++) {
      out.push(input[i]);
    }

    return out;
  };
}