Test whether this value is numerically equal to `other`

.

If both operands are doubles, they are equal if they have the same representation, except that:

- zero and minus zero (0.0 and -0.0) are considered equal. They both have the numerical value zero.
- NaN is not equal to anything, including NaN. If either operand is NaN, the result is always false.

If one operand is a double and the other is an int, they are equal if
the double has an integer value (finite with no fractional part) and
`identical(doubleValue.toInt(), intValue)`

is true.

If both operands are integers, they are equal if they have the same value.

Returns false if `other`

is not a num.

Notice that the behavior for NaN is non-reflexive. This means that
equality of double values is not a proper equality relation, as is
otherwise required of `operator==`

. Using NaN in, e.g., a HashSet
will fail to work. The behavior is the standard IEEE-754 equality of
doubles.

If you can avoid NaN values, the remaining doubles do have a proper equality relation, and can be used safely.

Use compareTo for a comparison that distinguishes zero and minus zero, and that considers NaN values as equal.

## Source

bool operator ==(Object other);