JSFiddle - React, Tailwind, and code Playground

JavaScript

var obj1 = {IMAGEURL: 'http://whatever.com/1'};
var obj2 = {IMAGEURL: 'http://whatever.com/2'};
var obj3 = {IMAGEURL: 'http://whatever.com/1'};

var arr = [obj1, obj2, obj3];
var uniqueArr = arr.filter(function(obj){
    if(obj.IMAGEURL in this) return false;
    return this[obj.IMAGEURL] = true;
}, {});
console.log(uniqueArr)