JS Hint – don’t make functions within a loop

You can just move the function outside the loop and pass a reference to it to map:

function mapCallback(item) {
    return {
        id : item[0],
        title : item[1],
    };
}
for (i = 0; i < Collection.length; i += 4) {
    data.push({
        items: Collection.slice(i, i + 4).map(mapCallback)
    });
}

Alternatively, you can use a JSHint directive to ignore function expressions inside loops. Just put this at the top of the file in question:

/*jshint loopfunc: true */