check if the array of objects have duplicate property values

isDuplicate.js

var values = [
    { name: 'someName1' },
    { name: 'someName2' },
    { name: 'someName4' },
    { name: 'someName2' }
];

var valueArr = values.map(function(item){ return item.name });
var isDuplicate = valueArr.some(function(item, idx){ 
    return valueArr.indexOf(item) != -1;
});
console.log(isDuplicate);

//http://stackoverflow.com/questions/30735465/how-can-i-check-if-the-array-of-objects-have-duplicate-property-values