Created
May 18, 2019 14:42
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fast deep equals in TypeScript
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| const isArray = Array.isArray; | |
| const keyList = Object.keys; | |
| const hasProp = Object.prototype.hasOwnProperty; | |
| export function isDeeplyEqual<T extends any>(a: T, b: T): boolean { | |
| if (a === b) { return true; } | |
| if (a && b && typeof a === 'object' && typeof b === 'object') { | |
| const arrA = isArray(a) | |
| , arrB = isArray(b); | |
| let i | |
| , length | |
| , key; | |
| if (arrA && arrB) { | |
| length = a.length; | |
| if (length !== b.length) { return false; } | |
| for (i = length; i-- !== 0;) { | |
| if (!isDeeplyEqual(a[i], b[i])) { return false; | |
| } } | |
| return true; | |
| } | |
| if (arrA !== arrB) { return false; } | |
| const dateA = a instanceof Date | |
| , dateB = b instanceof Date; | |
| if (dateA !== dateB) { return false; } | |
| if (dateA && dateB) { return a.getTime() === b.getTime(); } | |
| const regexpA = a instanceof RegExp | |
| , regexpB = b instanceof RegExp; | |
| if (regexpA !== regexpB) { return false; } | |
| if (regexpA && regexpB) { return a.toString() === b.toString(); } | |
| const keys = keyList(a); | |
| length = keys.length; | |
| if (length !== keyList(b).length) { | |
| return false; | |
| } | |
| for (i = length; i-- !== 0;) { | |
| if (!hasProp.call(b, keys[i])) { return false; | |
| } } | |
| for (i = length; i-- !== 0;) { | |
| key = keys[i]; | |
| if (!isDeeplyEqual(a[key], b[key])) { return false; } | |
| } | |
| return true; | |
| } | |
| return a !== a && b !== b; | |
| } |
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