Works with comparing 2 Objects too....
2 min read
const a = [1,2]; const b = [1,2]; if (a === b) console.log('Equal!');
If you'd tried this, then you KNOW
a === b will return false every time.
Why is that?
Because array variables are assigned by reference NOT by value.
a is just a pointer to the location of
[1,2] somewhere in memory.
While 'b' is another pointer to a different location in memory, that also happens to be storing
When you're checking if
a === b, you're really checking their member locations, and not the values they're pointing to.
So what gives?
Is there any easy way to check if the underlying arrays that are represented by
b are equal, WITHOUT having to do an element by element comparison?
Here's the quick cheat to get it done...
const d = [1,2,4,5,6]; const c = [1,2,4,5,6]; if (JSON.stringify(d) === JSON.stringify(c)) console.log('Equal!');
Why does this work?
And what the heck is
JSON.stringify(...) takes an array (or an object)and returns its string representation.
Will just return
'[7,8,9]'. Since the value is a string, you can compare it with the value of another array, that's also returned as a string with
This trick even works with double array (and multi-dimensional arrays in general). You can also compare objects this way, as long as properties of each object are in the same order.
If you want to compare if 2 arrays contain the same values, regardless of order, then just use
Array.sort() method to sort both arrays first, THEN use
JSON.stringify to compare then!
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