I am using the following code to try and generate a list showing the count of each item in the letters list within an AngularJS controller:
$scope.letters = ['a','b','c'];
$scope.letterdata = ['a','b','a','c','b','a'];
$scope.counts = $scope.letters.map(function (x) {
$scope.letterdata.filter(function (y) {
return (x == y);
}).length;
});
I would like to get [3,2,1] as the output, but this is showing as [null,null,null].
You're missing return statement inside map().
$scope.counts = $scope.letters.map(function (x) {
return $scope.letterdata.filter(function (y) {
^^^^^^
return (x == y);
}).length;
});
var letters = ['a', 'b', 'c'];
var letterdata = ['a', 'b', 'a', 'c', 'b', 'a'];
var counts = letters.map(function (x) {
return letterdata.filter(function (y) {
return(x == y);
}).length;
});
console.log(counts);but this is showing as
[null,null,null].
You should be getting [ undefined, undefined, undefined ] as nothing is returned, by default undefined is returned.
Equivalent code written using ES2015 arrow function.
$scope.letters.map(x => $scope.letterdata.filter(y => x == y).length)
var letters = ['a', 'b', 'c'];
var letterdata = ['a', 'b', 'a', 'c', 'b', 'a'];
var counts = letters.map(x => letterdata.filter(y => x == y).length);
console.log(counts);var list = ['a', 'b', 'c'];
var data = ['a', 'b', 'a', 'c', 'b', 'a'];
_.reduce(list, function(counts, value) {
counts.push(_.size(data) - _.size(_.without(data, value)));
return counts;
}, []);
