I'm trying to use Underscore's where to filter an array of objects, but I can't seem to figure out how to get it to filter multiple values for the same key. For example:

var itemsArr = [{name:"foo", color:"red"}, {name:"bar", color:"blue"}, {name:"bob", color:"yellow"}];

I'm trying to get it to return an array off all items with color red AND all items with color blue... Is this possible? I've tried

tempArr = _.where(itemsArr, {color:["red", "blue"]}); 

but that didn't work. If I have to just use _.filter and write out my own predicate I will, but I was just wondering if anyone else had tried to do this and found a solution.

I'm trying to use Underscore's where to filter an array of objects, but I can't seem to figure out how to get it to filter multiple values for the same key. For example:

var itemsArr = [{name:"foo", color:"red"}, {name:"bar", color:"blue"}, {name:"bob", color:"yellow"}];

I'm trying to get it to return an array off all items with color red AND all items with color blue... Is this possible? I've tried

tempArr = _.where(itemsArr, {color:["red", "blue"]}); 

but that didn't work. If I have to just use _.filter and write out my own predicate I will, but I was just wondering if anyone else had tried to do this and found a solution.

• javascript
• underscore.js

5 Answers 5

use filter and contains bination:

_.filter(itemsArr, function(item, index) {
  return _.contains(["red", "blue"], item.color);
})

Use a filter function:

_.filter(itemsArr,function(itm){return itm.color=='red' || itm.color=='blue'})

Can you run _.where twice and concat the two resulting arrays?

tempArr = _.where(itemsArr, {color: "red"}).concat(_.where(itemsArr, {color: "blue"}));

Here is the solution

 var itemsArr = [{name:"foo", color:"red"}, {name:"bar", color:"blue"}, {name:"bob", color:"red"}];
 var filter = ["red","blue"];
 var data = {};
 _.each(filter, function (item) { 
       data[item] = true; 
   });

 var returnData = _.filter(itemsArr, function (item) {
                    return data[item.color];
                 });

 console.log(returnData)

According to the documentation:

Looks through each value in the list, returning an array of all the values that contain all of the key-value pairs listed in properties.

You can also look at the source code if you'd like. Under the hood, where uses isMatch:

_.isMatch = function(object, attrs) {
    var keys = _.keys(attrs), length = keys.length;
    if (object == null) return !length;
    var obj = Object(object);
    for (var i = 0; i < length; i++) {
        var key = keys[i];
        if (attrs[key] !== obj[key] || !(key in obj)) return false;
    }
    return true;
};

Since you cannot have two identical keys, you cannot do what you would like. I would use filter, as you suggest.