Question

Assuming Array was not overwritten, why the following comparisons output false?

[] === new Array()
> false

[] === []
> false

Answer 1

Whether using the equality == operator or the strict equality === operator, if the operands are objects the result will be true only if both operands refer to the same object.

Your code creates two distinct arrays, both empty, so intuitively they might seem equal but that is not how the equals operators work.

Similarly something like [1,2,3] === [1,2,3] will be false. Again it is easy to think they should be equal, but the comparison is testing whether the arrays are the same array, not whether all of the elements in the array are equal.

On the other hand x === y will be true if both x and y refer to the same array.

For more information: https://developer.mozilla.org/en/JavaScript/Reference/Operators/Comparison_Operators