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feat(limitTo): limitTo filter accepts strings
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This allows strings to be filtered by limitTo, using the same methods

Closes #653
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@jtymes @pkozlowski-opensource
jtymes authored and pkozlowski-opensource committed Dec 19, 2012
1 parent 1e13544 commit 9e96d98
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83 changes: 50 additions & 33 deletions src/ng/filter/limitTo.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,80 +6,97 @@
* @function
*
* @description
* Creates a new array containing only a specified number of elements in an array. The elements
* are taken from either the beginning or the end of the source array, as specified by the
* value and sign (positive or negative) of `limit`.
* 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`.
*
* Note: This function is used to augment the `Array` type in Angular expressions. See
* {@link ng.$filter} for more information about Angular arrays.
*
* @param {Array} array Source array to be limited.
* @param {string|Number} limit The length of the returned array. If the `limit` number is
* positive, `limit` number of items from the beginning of the source array are copied.
* If the number is negative, `limit` number of items from the end of the source array are
* copied. The `limit` will be trimmed if it exceeds `array.length`
* @returns {Array} A new sub-array of length `limit` or less if input array had less than `limit`
* elements.
* @param {Array|string} input Source array or string to be limited.
* @param {string|number} limit The length of the returned array or string. If the `limit` number
* is positive, `limit` number of items from the beginning of the source array/string are copied.
* If the number is negative, `limit` number of items from the end of the source array/string
* are copied. The `limit` will be trimmed if it exceeds `array.length`
* @returns {Array|string} A new sub-array or substring of length `limit` or less if input array
* had less than `limit` elements.
*
* @example
<doc:example>
<doc:source>
<script>
function Ctrl($scope) {
$scope.numbers = [1,2,3,4,5,6,7,8,9];
$scope.limit = 3;
$scope.letters = "abcdefghi";
$scope.numLimit = 3;
$scope.letterLimit = 3;
}
</script>
<div ng-controller="Ctrl">
Limit {{numbers}} to: <input type="integer" ng-model="limit">
<p>Output: {{ numbers | limitTo:limit }}</p>
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>
</doc:source>
<doc:scenario>
it('should limit the numer array to first three items', function() {
expect(element('.doc-example-live input[ng-model=limit]').val()).toBe('3');
expect(binding('numbers | limitTo:limit')).toEqual('[1,2,3]');
it('should limit the number array to first three items', function() {
expect(element('.doc-example-live input[ng-model=numLimit]').val()).toBe('3');
expect(element('.doc-example-live input[ng-model=letterLimit]').val()).toBe('3');
expect(binding('numbers | limitTo:numLimit')).toEqual('[1,2,3]');
expect(binding('letters | limitTo:letterLimit')).toEqual('abc');
});
it('should update the output when -3 is entered', function() {
input('limit').enter(-3);
expect(binding('numbers | limitTo:limit')).toEqual('[7,8,9]');
input('numLimit').enter(-3);
input('letterLimit').enter(-3);
expect(binding('numbers | limitTo:numLimit')).toEqual('[7,8,9]');
expect(binding('letters | limitTo:letterLimit')).toEqual('ghi');
});
it('should not exceed the maximum size of input array', function() {
input('limit').enter(100);
expect(binding('numbers | limitTo:limit')).toEqual('[1,2,3,4,5,6,7,8,9]');
input('numLimit').enter(100);
input('letterLimit').enter(100);
expect(binding('numbers | limitTo:numLimit')).toEqual('[1,2,3,4,5,6,7,8,9]');
expect(binding('letters | limitTo:letterLimit')).toEqual('abcdefghi');
});
</doc:scenario>
</doc:example>
*/
function limitToFilter(){
return function(array, limit) {
if (!(array instanceof Array)) return array;
return function(input, limit) {
if (!isArray(input) && !isString(input)) return input;

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;

// check that array is iterable
if (!array || !(array instanceof Array))
return out;

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

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

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

return out;
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29 changes: 24 additions & 5 deletions test/ng/filter/limitToSpec.js
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Expand Up @@ -2,23 +2,29 @@

describe('Filter: limitTo', function() {
var items;
var str
var limitTo;

beforeEach(inject(function($filter) {
items = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
str = "tuvwxyz";
limitTo = $filter('limitTo');
}));


it('should return the first X items when X is positive', function() {
expect(limitTo(items, 3)).toEqual(['a', 'b', 'c']);
expect(limitTo(items, '3')).toEqual(['a', 'b', 'c']);
expect(limitTo(str, 3)).toEqual("tuv");
expect(limitTo(str, '3')).toEqual("tuv");
});


it('should return the last X items when X is negative', function() {
expect(limitTo(items, -3)).toEqual(['f', 'g', 'h']);
expect(limitTo(items, '-3')).toEqual(['f', 'g', 'h']);
expect(limitTo(str, -3)).toEqual("xyz");
expect(limitTo(str, '-3')).toEqual("xyz");
});


Expand All @@ -30,23 +36,36 @@ describe('Filter: limitTo', function() {
expect(limitTo(items, undefined)).toEqual([]);
});

it('should return an empty string when X cannot be parsed', function() {
expect(limitTo(str, 'bogus')).toEqual("");
expect(limitTo(str, 'null')).toEqual("");
expect(limitTo(str, 'undefined')).toEqual("");
expect(limitTo(str, null)).toEqual("");
expect(limitTo(str, undefined)).toEqual("");
});

it('should return an empty array when input is not Array type', function() {
expect(limitTo('bogus', 1)).toEqual('bogus');
expect(limitTo(null, 1)).toEqual(null);
expect(limitTo(undefined, 1)).toEqual(undefined);

it('should return input if not String or Array', function() {
expect(limitTo(1,1)).toEqual(1);
expect(limitTo(null, 1)).toEqual(null);
expect(limitTo(undefined, 1)).toEqual(undefined);
expect(limitTo({}, 1)).toEqual({});
});


it('should return a copy of input array if X is exceeds array length', function () {
expect(limitTo(items, 19)).toEqual(items);
expect(limitTo(items, 9)).toEqual(items);
expect(limitTo(items, '9')).toEqual(items);
expect(limitTo(items, -9)).toEqual(items);
expect(limitTo(items, '-9')).toEqual(items);

expect(limitTo(items, 9)).not.toBe(items);
});

it('should return the entire string if X exceeds input length', function() {
expect(limitTo(str, 9)).toEqual(str);
expect(limitTo(str, '9')).toEqual(str);
expect(limitTo(str, -9)).toEqual(str);
expect(limitTo(str, '-9')).toEqual(str);
})
});

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