JSFiddle - React, Tailwind, and code Playground

JavaScript

var array1 = [{'578': '2'}, {'123': '18'}, {'323': '5'}];
var array2 = [{'123': '18'}, {'578': '1'}, {'323': '3'}];
var removed = exists = [];
for(var k in array2){
	var found = k;
	for(var x in array2){
		if(JSON.stringify(array2[k]) ==  JSON.stringify(array1[x])){
			found = true;
			break;
		}
	}
	if(found !== true){
		removed.push(array2[found]);
	}
}

array2 = removed;
console.log(array2);