Performs a deep comparison between two values to determine if they are equivalent.
- Check if the two values are identical.
- Check if both values are
Date
objects with the same time, usingDate.prototype.getTime()
. - Check if both values are non-object values with an equivalent value (strict comparison).
- Check if only one value is
null
orundefined
or if their prototypes differ. - If none of the above conditions are met, use
Object.keys()
to check if both values have the same number of keys. - Use
Array.prototype.every()
to check if every key ina
exists inb
and if they are equivalent by callingequals()
recursively.
代码实现
const equals = (a, b) => {
if (a === b) return true;
if (a instanceof Date && b instanceof Date)
return a.getTime() === b.getTime();
if (!a || !b || (typeof a !== 'object' && typeof b !== 'object'))
return a === b;
if (a.prototype !== b.prototype) return false;
const keys = Object.keys(a);
if (keys.length !== Object.keys(b).length) return false;
return keys.every(k => equals(a[k], b[k]));
};
equals(
{ a: [2, { e: 3 }], b: [4], c: 'foo' },
{ a: [2, { e: 3 }], b: [4], c: 'foo' }
); // true
equals([1, 2, 3], { 0: 1, 1: 2, 2: 3 }); // true
翻译自:https://www.30secondsofcode.org/js/s/deep-equality-comparison