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re-adding 649f62

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Jeremy Ashkenas
2011-12-07 09:35:07 -05:00
parent cf1d69227b
commit 770f0876b3
2 changed files with 21 additions and 11 deletions
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20
test/collections.js
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@@ -77,13 +77,13 @@ $(document).ready(function() {
ok(ifnull instanceof TypeError, 'handles a null (without inital value) properly');
ok(_.reduce(null, function(){}, 138) === 138, 'handles a null (with initial value) properly');
equals(_.reduce([], function(){}, undefined), undefined, 'undefined can be passed as a special case');
raises(function() { _.reduce([], function(){}); }, TypeError, 'throws an error for empty arrays with no initial value');
// Sparse arrays:
var sparseArray = [];
sparseArray[100] = 10;
sparseArray[200] = 20;
equals(_.reduce(sparseArray, function(a, b){ return a + b }), 30, 'initially-sparse arrays with no memo');
var sparseArray = [];
sparseArray[0] = 20;
sparseArray[2] = -5;
equals(_.reduce(sparseArray, function(a, b){ return a - b }), 25, 'initially-sparse arrays with no memo');
});
test('collections: reduceRight', function() {
@@ -105,6 +105,14 @@ $(document).ready(function() {
ok(ifnull instanceof TypeError, 'handles a null (without inital value) properly');
ok(_.reduceRight(null, function(){}, 138) === 138, 'handles a null (with initial value) properly');
equals(_.reduceRight([], function(){}, undefined), undefined, 'undefined can be passed as a special case');
raises(function() { _.reduceRight([], function(){}); }, TypeError, 'throws an error for empty arrays with no initial value');
var sparseArray = [];
sparseArray[0] = 20;
sparseArray[2] = -5;
equals(_.reduceRight(sparseArray, function(a, b){ return a - b }), -25, 'initially-sparse arrays with no memo');
});
test('collections: detect', function() {

12
underscore.js
View File

@@ -108,7 +108,7 @@
// **Reduce** builds up a single result from a list of values, aka `inject`,
// or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
_.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
var initial = memo !== void 0;
var initial = arguments.length > 2;
if (obj == null) obj = [];
if (nativeReduce && obj.reduce === nativeReduce) {
if (context) iterator = _.bind(iterator, context);
@@ -122,20 +122,22 @@
memo = iterator.call(context, memo, value, index, list);
}
});
if (!initial) throw new TypeError("Reduce of empty array with no initial value");
if (!initial) throw new TypeError('Reduce of empty array with no initial value');
return memo;
};
// The right-associative version of reduce, also known as `foldr`.
// Delegates to **ECMAScript 5**'s native `reduceRight` if available.
_.reduceRight = _.foldr = function(obj, iterator, memo, context) {
var initial = arguments.length > 2;
if (obj == null) obj = [];
if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
if (context) iterator = _.bind(iterator, context);
return memo !== void 0 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
}
var reversed = (_.isArray(obj) ? obj.slice() : _.toArray(obj)).reverse();
return _.reduce(reversed, iterator, memo, context);
var reversed = _.toArray(obj).reverse();
if (context && !initial) iterator = _.bind(iterator, context);
return initial ? _.reduce(reversed, iterator, memo, context) : _.reduce(reversed, iterator);
};
// Return the first value which passes a truth test. Aliased as `detect`.