var a = {x: '1'};
var b = {x: '2'};
JSON.structure(a).compare(b); // true
var a = {x: '1'};
var b = {x: 2};
JSON.structure(a).compare(b); // Error: x (wrong type)
var a = {x: '1'};
var b = {y: '2'};
JSON.structure(a).compare(b); // Error: x (missing value)