Remove Duplicate objects from JSON Array

Question

I have an array that looks like this:

var standardsList = [
    {"Grade": "Math K", "Domain": "Counting & Cardinality"},
    {"Grade": "Math K", "Domain": "Counting & Cardinality"},
    {"Grade": "Math K", "Domain": "Counting & Cardinality"},
    {"Grade": "Math K", "Domain": "Counting & Cardinality"},
    {"Grade": "Math K", "Domain": "Geometry"},
    {"Grade": "Math 1", "Domain": "Counting & Cardinality"},
    {"Grade": "Math 1", "Domain": "Counting & Cardinality"},
    {"Grade": "Math 1", "Domain": "Orders of Operation"},
    {"Grade": "Math 2", "Domain": "Geometry"},
    {"Grade": "Math 2", "Domain": "Geometry"}
];

And I need to remove the duplicates so that something like this remains:

var standardsList = [
    {"Grade": "Math K", "Domain": "Counting & Cardinality"},
    {"Grade": "Math K", "Domain": "Geometry"},
    {"Grade": "Math 1", "Domain": "Counting & Cardinality"},
    {"Grade": "Math 1", "Domain": "Orders of Operation"},
    {"Grade": "Math 2", "Domain": "Geometry"}
];

I've tried installing underscore.js and using ._uniq but that only seems to work when a single key:value pair appears in the object. I can't seem to get it to work across multiple keys.

When I try something like:

var uniqueStandards = _.uniq(standardsList, function(item, key, Domain){
    return item.Domain;
});

I only get the first three unique values (one per grade). But I need all the unique values across both grade and domain. Is there a simple way to feed both keys to the _.uniq function?

Ultimately, I need a list with the each unique grade as the header and the unique domains as the list items to pass into an HTML page. I may be going about this wrong, so if there is an easier way to accomplish that end goal, I am open to ideas.

Thanks in advance!

Edit: Getting some good responses and wanted to clarify what my end goal was. I'm trying to create a series of lists in HTML of the form:

<div>
    <h3>Math K</h3>
    <li>Counting & Cardinality</li>
    <li>Geometry</li>
</div>
<div>
    <h3>Math 1</h3>
    <li>Counting & Cardinality</li>
    <li>Orders of Operation</li>
</div>
<div>
    <h3>Math 2</h3>
    <li>Geometry</li>
</div>

My original though was to create an array and push that into the <div> element on the page with $("#divid").append(array)

Answer 1

function arrUnique(arr) {
    var cleaned = [];
    arr.forEach(function(itm) {
        var unique = true;
        cleaned.forEach(function(itm2) {
            if (_.isEqual(itm, itm2)) unique = false;
        });
        if (unique)  cleaned.push(itm);
    });
    return cleaned;
}

var standardsList = arrUnique(standardsList);

FIDDLE

This will return

var standardsList = [
    {"Grade": "Math K", "Domain": "Counting & Cardinality"},
    {"Grade": "Math K", "Domain": "Geometry"},
    {"Grade": "Math 1", "Domain": "Counting & Cardinality"},
    {"Grade": "Math 1", "Domain": "Orders of Operation"},
    {"Grade": "Math 2", "Domain": "Geometry"}
];

Which is exactly what you asked for ?