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Improve compliance with Array methods in ES5 when passed a null value. (ES5 Array methods treat null like [])

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Ryan W Tenney
2010-12-06 23:30:43 -05:00
parent e63f44f798
commit cdcf18b79c
3 changed files with 47 additions and 5 deletions
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23
underscore.js
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@@ -68,6 +68,7 @@
// Delegates to **ECMAScript 5**'s native `forEach` if available.
var each = _.each = _.forEach = function(obj, iterator, context) {
var value;
if (obj == null) return;
if (nativeForEach && obj.forEach === nativeForEach) {
obj.forEach(iterator, context);
} else if (_.isNumber(obj.length)) {
@@ -86,8 +87,9 @@
// Return the results of applying the iterator to each element.
// Delegates to **ECMAScript 5**'s native `map` if available.
_.map = function(obj, iterator, context) {
if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
var results = [];
if (obj == null) return results;
if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
each(obj, function(value, index, list) {
results[results.length] = iterator.call(context, value, index, list);
});
@@ -98,6 +100,7 @@
// or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
_.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
var initial = memo !== void 0;
if (obj == null) obj = [];
if (nativeReduce && obj.reduce === nativeReduce) {
if (context) iterator = _.bind(iterator, context);
return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
@@ -105,16 +108,19 @@
each(obj, function(value, index, list) {
if (!initial && index === 0) {
memo = value;
initial = true;
} else {
memo = iterator.call(context, memo, value, index, list);
}
});
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) {
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);
@@ -139,8 +145,9 @@
// Delegates to **ECMAScript 5**'s native `filter` if available.
// Aliased as `select`.
_.filter = _.select = function(obj, iterator, context) {
if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
var results = [];
if (obj == null) return results;
if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
each(obj, function(value, index, list) {
if (iterator.call(context, value, index, list)) results[results.length] = value;
});
@@ -150,6 +157,7 @@
// Return all the elements for which a truth test fails.
_.reject = function(obj, iterator, context) {
var results = [];
if (obj == null) return results;
each(obj, function(value, index, list) {
if (!iterator.call(context, value, index, list)) results[results.length] = value;
});
@@ -161,8 +169,9 @@
// Aliased as `all`.
_.every = _.all = function(obj, iterator, context) {
iterator = iterator || _.identity;
if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
var result = true;
if (obj == null) return result;
if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
each(obj, function(value, index, list) {
if (!(result = result && iterator.call(context, value, index, list))) return breaker;
});
@@ -174,8 +183,9 @@
// Aliased as `any`.
var any = _.some = _.any = function(obj, iterator, context) {
iterator = iterator || _.identity;
if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
var result = false;
if (obj == null) return result;
if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
each(obj, function(value, index, list) {
if (result = iterator.call(context, value, index, list)) return breaker;
});
@@ -185,8 +195,9 @@
// Determine if a given value is included in the array or object using `===`.
// Aliased as `contains`.
_.include = _.contains = function(obj, target) {
if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
var found = false;
if (obj == null) return found;
if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
any(obj, function(value) {
if (found = value === target) return true;
});
@@ -346,6 +357,7 @@
// item in an array, or -1 if the item is not included in the array.
// Delegates to **ECMAScript 5**'s native `indexOf` if available.
_.indexOf = function(array, item) {
if (array == null) return -1;
if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
for (var i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
return -1;
@@ -354,6 +366,7 @@
// Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
_.lastIndexOf = function(array, item) {
if (array == null) return -1;
if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
var i = array.length;
while (i--) if (array[i] === item) return i;