Filter a number of javascript objects using an array of values for one key

Question

I want to filter the following objects by category_id using the following array of category_id values:

[19012000, 19012001, 19012002, 19012003, 19012004, 190         


        

Answer 1

indexOf() with a string and a number

var a = [123]; 
console.log(a.indexOf(123));  //true   
console.log(a.indexOf("123"));  //false

Your code is not working because you are comparing a string in your object to the numbers in your array.

category_id.indexOf(+n.category_id)

or

category_id.indexOf(parseInt(n.category_id, 10))

Answer 2

I don't see any reason to use _.first here? The rest of your filter statement looks good, altough you may swap the indexOf call for _.contains:

var postDates = _.filter(goodDates, function(n){
    return _.contains(category_id, n.category_id);
});