(function(root) {
Underscore-contrib (underscore.array.selectors.js 0.0.1) (c) 2013 Michael Fogus, DocumentCloud and Investigative Reporters & Editors Underscore-contrib may be freely distributed under the MIT license.
(function(root) {
Establish the root object, window
in the browser, or global
on the server.
var _ = root._ || require('underscore');
Create quick reference variables for speed access to core prototypes.
var slice = Array.prototype.slice,
concat = Array.prototype.concat;
var existy = function(x) { return x != null; };
var truthy = function(x) { return (x !== false) && existy(x); };
var isSeq = function(x) { return (_.isArray(x)) || (_.isArguments(x)); };
_.mixin({
Returns the second element of an array. Passing n will return all but
the first of the head N values in the array. The guard check allows it
to work with _.map
.
second: function(array, n, guard) {
if (array == null) return void 0;
return (n != null) && !guard ? slice.call(array, 1, n) : array[1];
},
A function to get at an index into an array
nth: function(array, index) {
if ((index < 0) || (index > array.length - 1)) throw Error("Attempting to index outside the bounds of the array.");
return array[index];
},
Takes all items in an array while a given predicate returns truthy.
takeWhile: function(array, pred) {
if (!isSeq(array)) throw new TypeError;
var sz = _.size(array);
for (var index = 0; index < sz; index++) {
if(!truthy(pred(array[index]))) {
break;
}
}
return _.take(array, index);
},
Drops all items from an array while a given predicate returns truthy.
dropWhile: function(array, pred) {
if (!isSeq(array)) throw new TypeError;
var sz = _.size(array);
for (var index = 0; index < sz; index++) {
if(!truthy(pred(array[index])))
break;
}
return _.drop(array, index);
},
Returns an array with two internal arrays built from taking an original array and spliting it at the index where a given function goes falsey.
splitWith: function(array, pred) {
return [_.takeWhile(pred, array), _.dropWhile(pred, array)];
},
Takes an array and partitions it as the given predicate changes truth sense.
partitionBy: function(array, fun){
if (_.isEmpty(array) || !existy(array)) return [];
var fst = _.first(array);
var fstVal = fun(fst);
var run = concat.call([fst], _.takeWhile(_.rest(array), function(e) {
return _.isEqual(fstVal, fun(e));
}));
return concat.call([run], _.partitionBy(_.drop(array, _.size(run)), fun));
},
Returns the 'best' value in an array based on the result of a given function.
best: function(array, fun) {
return _.reduce(array, function(x, y) {
return fun(x, y) ? x : y;
});
},
Returns an array of existy results of a function over an source array.
keep: function(array, fun) {
if (!isSeq(array)) throw new TypeError("expected an array as the first argument");
return _.filter(_.map(array, function(e) {
return fun(e);
}), existy);
}
});
})(this);