Created
June 20, 2019 05:25
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Objects equality deep checking
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export function objectsEqual(...objects: any[]) { | |
let leftChain: any[] | |
let rightChain: any[] | |
const _compareTwoObjects = (x: any, y: any) => { | |
// 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(const p in y) { | |
if(y.hasOwnProperty(p)) { | |
if(y.hasOwnProperty(p) !== x.hasOwnProperty(p)) return false | |
else if(typeof y[p] !== typeof x[p]) return false | |
} | |
} | |
for(const p in x) { | |
if(x.hasOwnProperty(p)) { | |
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(!_compareTwoObjects(x[p], y[p])) return false | |
leftChain.pop() | |
rightChain.pop() | |
break | |
default: | |
if(x[p] !== y[p]) return false | |
break | |
} | |
} | |
} | |
return true | |
} | |
if(objects.length < 1) return true | |
for(let i = 1; i < objects.length; i++) { | |
leftChain = [] | |
rightChain = [] | |
if(!_compareTwoObjects(objects[0], objects[i])) return false | |
} | |
return true | |
} |
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