DOMPointReadOnly: y property
Note: This feature is available in Web Workers.
The DOMPointReadOnly interface's
y property holds the vertical coordinate, y, for a
read-only point in space.
If your script needs to be able to change the value
of this property, you should instead use the DOMPoint object.
In general, positive values of y mean downward, and negative values of
y mean upward, assuming no transforms have resulted in a reversal.
Value
A double-precision floating-point value indicating the y coordinate's value for the
point. This value is unrestricted, meaning that it is allowed to be
infinite or invalid (that is, its value may be NaN or ±Infinity).