The DOMPointInit dictionary's z property is used to specify the z-coordinate of a point in 2D or 3D space when either creating or serializing to JSON a DOMPoint or DOMPointReadOnly object.

Typically, a z value of 0 represents the plane of the screen. As the value increases, the point moves outward from the screen toward the user. As the value decreases, the point moves farther from the user, with negative values being behind the screen, receding into the distance.

Of course, if transforms have been applied, the axes may have changed orientation.


var DOMPointInit = {
  z: zPos

DOMPointInit.z = zPos;

var zPos = DOMPointInit.z;


A double-precision floating-point value indicating the point's z-coordinate. This value is unrestricted, meaning that it is allowed to be infinite or invalid (that is, its value may be NaN or ±Infinity).

There are two methods which use DOMPointInit:

  • The static function DOMPointReadOnly.fromPoint() takes an object that complies with DOMPointInit as its sole input parameter, to specify the coordinates and perspective value of the new point to be created. This method is, by inheritance, also available as DOMPoint.fromPoint().
  • The DOMPointReadOnly.toJSON() method returns a DOMPointInit object that describes the same point as the original point. By inheritance, this method is also available as DOMPoint.toJSON().

If this property is missing when the DOMPointInit object is passed into fromPoint(), the value is assumed to be 0 by default.


Specification Status Comment
Geometry Interfaces Module Level 1
The definition of 'z' in that specification.
Candidate Recommendation Initial definition

Browser compatibility

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