hd-utils
Version:
A handy utils for modern JS developers
103 lines (102 loc) • 3.69 kB
JavaScript
/**
* @description It compares two arguments and returns true if they are equal, false if they are not
* @example deepCompareObjects({a:1}, {a:1}) // true
* @example deepCompareObjects([1,2,3], [1,2,3]) // true
* @example deepCompareObjects([1,2,3], [1,2,5]) // false
* @example deepCompareObjects(true ,false) // false
*/
export default function deepCompare(...args) {
let i, l, leftChain, rightChain;
const compare2Objects = (x, y) => {
let p;
// remember that NaN === NaN returns false
// and isNaN(undefined) returns true
if (isNaN(x) &&
isNaN(y) &&
typeof x === 'number' &&
typeof y === 'number') {
return true;
}
// Compare primitives and functions.
// Check if both arguments link to the same object.
// Especially useful on the step where we compare prototypes
if (x === y) {
return true;
}
// Works in case when functions are created in constructor.
// Comparing dates is a common scenario. Another built-ins?
// We can even handle functions passed across iframes
if ((typeof x === 'function' && typeof y === 'function') ||
(x instanceof Date && y instanceof Date) ||
(x instanceof RegExp && y instanceof RegExp) ||
(x instanceof String && y instanceof String) ||
(x instanceof Number && y instanceof Number)) {
return x.toString() === y.toString();
}
// At last checking prototypes as good as we can
if (!(x instanceof Object && y instanceof Object)) {
return false;
}
if (x.isPrototypeOf(y) || y.isPrototypeOf(x)) {
return false;
}
if (x.constructor !== y.constructor) {
return false;
}
if (x.prototype !== y.prototype) {
return false;
}
// Check for infinitive linking loops
if (leftChain.indexOf(x) > -1 || rightChain.indexOf(y) > -1) {
return false;
}
// Quick checking of one object being a subset of another.
// todo: cache the structure of arguments[0] for performance
for (p in y) {
if (y.hasOwnProperty(p) !== x.hasOwnProperty(p)) {
return false;
}
else if (typeof y[p] !== typeof x[p]) {
return false;
}
}
for (p in x) {
if (y.hasOwnProperty(p) !== x.hasOwnProperty(p)) {
return false;
}
else if (typeof y[p] !== typeof x[p]) {
return false;
}
switch (typeof x[p]) {
case 'object':
case 'function':
leftChain.push(x);
rightChain.push(y);
if (!compare2Objects(x[p], y[p])) {
return false;
}
leftChain.pop();
rightChain.pop();
break;
default:
if (x[p] !== y[p]) {
return false;
}
break;
}
}
return true;
};
if (args.length < 1) {
return true; //Die silently? Don't know how to handle such case, please help...
// throw "Need two or more arguments to compare";
}
for (i = 1, l = args.length; i < l; i++) {
leftChain = []; //Todo: this can be cached
rightChain = [];
if (!compare2Objects(args[0], args[i])) {
return false;
}
}
return true;
}