DOMPointInit.y - Web APIs 编辑

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

In general, the value of y increases to the right and decreases to the left, becoming negative to the left of the origin. This may change if transforms have been applied causing the axes' orientation to change.

Syntax

var DOMPointInit = {
  y: yPos
};

DOMPointInit.y = yPos;

var yPos = DOMPointInit.y;

Value

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

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

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().

Specifications

Browser compatibility

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