Phaser 4 -- Actions & Utility Functions

Phaser.Actions namespace for batch operations on Game Object arrays, plus Phaser.Utils.Array, Phaser.Utils.Objects, and Phaser.Utils.String helper functions.

Related skills: ../groups-and-containers/SKILL.md, ../sprites-and-images/SKILL.md

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Quick Start

// Create 20 sprites and batch-position them in a grid
const sprites = [];
for (let i = 0; i < 20; i++) {
    sprites.push(this.add.sprite(0, 0, 'gem'));
}

// Arrange into a 5x4 grid
Phaser.Actions.GridAlign(sprites, {
    width: 5,
    height: 4,
    cellWidth: 64,
    cellHeight: 64,
    x: 100,
    y: 100
});

// Fade alpha from 0 to 1 across all sprites
Phaser.Actions.Spread(sprites, 'alpha', 0, 1);

// Offset each sprite's x by 10, with a step of 2 per item
Phaser.Actions.IncX(sprites, 10, 2);

// Works with Groups too
const group = this.add.group({ key: 'star', repeat: 11 });
Phaser.Actions.PlaceOnCircle(group.getChildren(), new Phaser.Geom.Circle(400, 300, 200));

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Core Concepts

The Actions Pattern

Every Action in Phaser.Actions follows the same pattern:

1. First argument is always an array of Game Objects (or any objects with the required public properties like x, y, alpha, etc.).
2. Returns the same array, enabling chaining or pass-through.
3. Works with Groups by passing group.getChildren().
4. Actions do NOT store state. They are one-shot batch operations.

PropertyValueSet and PropertyValueInc

Most Set/Inc actions delegate to two core functions:

• PropertyValueSet(items, key, value, step, index, direction) -- Sets items[i][key] = value + (i * step).
• PropertyValueInc(items, key, value, step, index, direction) -- Adds items[i][key] += value + (i * step).

The step parameter adds an incremental offset per item. The index and direction parameters control iteration start point and order (1 = forward, -1 = backward).

Geometry-Based Placement

Actions like PlaceOnCircle, PlaceOnLine, RandomRectangle, etc. accept Phaser geometry objects (Phaser.Geom.Circle, Phaser.Geom.Line, etc.), NOT Game Object shapes. If using a Phaser.GameObjects.Circle, pass its .geom property instead.

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All Actions

Property Setters

Action	Signature	Description
SetX	(items, value, step?, index?, direction?)	Set x property
SetY	(items, value, step?, index?, direction?)	Set y property
SetXY	(items, x, y?, stepX?, stepY?, index?, direction?)	Set both x and y; y defaults to x
SetAlpha	(items, value, step?, index?, direction?)	Set alpha
SetBlendMode	(items, value, index?, direction?)	Set blend mode
SetDepth	(items, value, step?, index?, direction?)	Set render depth
SetHitArea	(items, hitArea?, callback?)	Set interactive hit area
SetOrigin	(items, originX, originY?, stepX?, stepY?, index?, direction?)	Set origin point
SetRotation	(items, value, step?, index?, direction?)	Set rotation (radians)
SetScale	(items, scaleX, scaleY?, stepX?, stepY?, index?, direction?)	Set both scale axes
SetScaleX	(items, value, step?, index?, direction?)	Set scaleX
SetScaleY	(items, value, step?, index?, direction?)	Set scaleY
SetScrollFactor	(items, x, y?, stepX?, stepY?, index?, direction?)	Set scroll factor
SetScrollFactorX	(items, value, step?, index?, direction?)	Set horizontal scroll factor
SetScrollFactorY	(items, value, step?, index?, direction?)	Set vertical scroll factor
SetTint	(items, topLeft, topRight?, bottomLeft?, bottomRight?)	Set tint color(s)
SetVisible	(items, value, index?, direction?)	Set visibility
PropertyValueSet	(items, key, value, step?, index?, direction?)	Generic: set any named property

Property Incrementers

Action	Signature	Description
IncX	(items, value, step?, index?, direction?)	Add to x
IncXY	(items, x, y?, stepX?, stepY?, index?, direction?)	Add to x and y
IncY	(items, value, step?, index?, direction?)	Add to y
IncAlpha	(items, value, step?, index?, direction?)	Add to alpha
Angle	(items, value, step?, index?, direction?)	Add to angle (degrees)
Rotate	(items, value, step?, index?, direction?)	Add to rotation (radians)
ScaleX	(items, value, step?, index?, direction?)	Add to scaleX
ScaleXY	(items, scaleX, scaleY?, stepX?, stepY?, index?, direction?)	Add to both scale axes
ScaleY	(items, value, step?, index?, direction?)	Add to scaleY
PropertyValueInc	(items, key, value, step?, index?, direction?)	Generic: increment any named property

Placement on Geometry

Action	Signature	Description
PlaceOnCircle	(items, circle, startAngle?, endAngle?)	Evenly space on circle perimeter
PlaceOnEllipse	(items, ellipse, startAngle?, endAngle?)	Evenly space on ellipse perimeter
PlaceOnLine	(items, line)	Evenly space along a line
PlaceOnRectangle	(items, rect, shift?)	Evenly space on rectangle perimeter
PlaceOnTriangle	(items, triangle, stepRate?)	Evenly space on triangle perimeter
RandomCircle	(items, circle)	Random positions within a circle
RandomEllipse	(items, ellipse)	Random positions within an ellipse
RandomLine	(items, line)	Random positions along a line
RandomRectangle	(items, rect)	Random positions within a rectangle
RandomTriangle	(items, triangle)	Random positions within a triangle

Layout and Alignment

Action	Signature	Description
GridAlign	(items, config)	Arrange in grid; config: { width, height, cellWidth, cellHeight, position, x, y }
AlignTo	(items, position, offsetX?, offsetY?)	Chain-align each item next to the previous one using Phaser.Display.Align constants
FitToRegion	(items, scaleMode?, region?, itemCoverage?)	Scale/position each GO to fill a rectangle (v4.0.0+). scaleMode: 0=stretch, -1=fit inside, 1=cover outside

Distribution and Interpolation

Action	Signature	Description
Spread	(items, property, min, max, inc?)	Linearly distribute a property from min to max across all items
SmoothStep	(items, property, min, max, inc?)	Distribute using Hermite smoothstep interpolation
SmootherStep	(items, property, min, max, inc?)	Distribute using Ken Perlin's smootherstep

Rotation and Movement

Action	Signature	Description
RotateAround	(items, point, angle)	Rotate all items around a point (radians)
RotateAroundDistance	(items, point, angle, distance)	Rotate around a point at a fixed distance
ShiftPosition	(items, x, y, direction?, output?)	Snake-like: move head to x/y, each item takes position of the previous
WrapInRectangle	(items, rect, padding?)	Wrap x/y to stay within rectangle bounds

Queries and Iteration

Action	Signature	Description
GetFirst	(items, compare, index?)	Find first item matching all properties in compare object
GetLast	(items, compare, index?)	Find last item matching all properties in compare object
Call	(items, callback, context)	Invoke callback for each item
Shuffle	(items)	Randomly reorder the array (Fisher-Yates)
ToggleVisible	(items)	Toggle visible on each item
PlayAnimation	(items, key, ignoreIfPlaying?)	Play animation on all items with an anims component

Effects (v4.0.0+)

Action	Signature	Description
AddEffectBloom	(items, config?)	Add Bloom filter effect to a Camera or GO. Returns { parallelFilters, threshold, blur }[]
AddEffectShine	(items, config?)	Add Shine filter effect
AddMaskShape	(items, config?)	Apply a shape-based mask (circle, square, rectangle, ellipse) with optional blur

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Array Utilities

Namespace: Phaser.Utils.Array

Function	Signature	Description
Add	(array, item, limit?, callback?, context?)	Add item(s) if not already present; optional size limit
AddAt	(array, item, index?, limit?, callback?, context?)	Insert item(s) at index
BringToTop	(array, item)	Move item to end of array
CountAllMatching	(array, property, value, startIndex?, endIndex?)	Count items where property equals value
Each	(array, callback, context, ...args)	Iterate with callback; passes item + extra args
EachInRange	(array, callback, context, startIndex, endIndex, ...args)	Iterate a slice with callback
FindClosestInSorted	(value, array, key?)	Binary-search style closest match in sorted array
Flatten	(array, output?)	Flatten nested arrays into a single array
GetAll	(array, property?, value?, startIndex?, endIndex?)	Filter items matching property/value
GetFirst	(array, property?, value?, startIndex?, endIndex?)	First item matching property/value
GetRandom	(array, startIndex?, length?)	Return a random element
MoveAbove	(array, item1, item2)	Move item2 directly above item1
MoveBelow	(array, item1, item2)	Move item2 directly below item1
MoveDown	(array, item)	Move item one position toward index 0
MoveTo	(array, item, index)	Move item to specific index
MoveUp	(array, item)	Move item one position toward end
NumberArray	(start, end, prefix?, suffix?)	Generate [start..end] range; optional string prefix/suffix
NumberArrayStep	(start?, end?, step?)	Generate range with custom step size
QuickSelect	(array, k, left?, right?, compare?)	Partial sort: kth smallest element in-place
Range	(a, b, options?)	Generate array from range config
Remove	(array, item, callback?, context?)	Remove item(s) from array
RemoveAt	(array, index, callback?, context?)	Remove item at index
RemoveBetween	(array, startIndex, endIndex, callback?, context?)	Remove items in range
RemoveRandomElement	(array, startIndex?, length?)	Remove and return a random element
Replace	(array, oldItem, newItem)	Swap one item for another
RotateLeft	(array, total?)	Shift elements left; last wraps to front
RotateRight	(array, total?)	Shift elements right; first wraps to end
SafeRange	(array, startIndex, endIndex, throwError?)	Validate index range is within bounds
SendToBack	(array, item)	Move item to index 0
SetAll	(array, property, value, startIndex?, endIndex?)	Set a property on all items in range
Shuffle	(array)	Fisher-Yates shuffle; modifies in-place
SortByDigits	(array)	Sort strings by embedded numeric values
SpliceOne	(array, index)	Fast single-element splice
StableSort	(array, compare?)	Guaranteed stable sort (merge sort fallback for engines without native stable sort)
Swap	(array, item1, item2)	Swap two items in-place

Also includes Phaser.Utils.Array.Matrix sub-namespace for 2D matrix operations.

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Object Utilities

Namespace: Phaser.Utils.Objects

Function	Signature	Description
Clone	(obj)	Shallow clone of object
DeepCopy	(obj)	Recursive deep copy of object or array
Extend	(target, ...sources)	jQuery-style extend; copies properties from sources to target
GetAdvancedValue	(source, key, defaultValue)	Like GetValue but resolves random/callback config values
GetFastValue	(source, key, defaultValue?)	Top-level-only property lookup; no dot-path support. Faster than GetValue
GetMinMaxValue	(source, key, min, max, defaultValue)	Get value clamped between min and max
GetValue	(source, key, defaultValue, altSource?)	Dot-path property lookup (e.g. 'render.screen.width'). Falls back to altSource then defaultValue
HasAll	(source, keys)	True if source has ALL listed keys
HasAny	(source, keys)	True if source has ANY listed key
HasValue	(source, key)	True if source has the key
IsPlainObject	(obj)	True if obj is a plain {} object (not DOM, not window)
Merge	(obj1, obj2)	Merge obj2 into a clone of obj1
MergeRight	(obj1, obj2)	Merge obj1 into a clone of obj2
Pick	(source, keys)	Return new object with only the specified keys
SetValue	(source, key, value)	Set a dot-path property value

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String Utilities

Namespace: Phaser.Utils.String

Function	Signature	Description
Format	(string, values)	Replace %1, %2, etc. markers with array values
Pad	(str, len?, pad?, dir?)	Pad string to length. dir: 1=left, 2=right, default=both
RemoveAt	(string, index)	Remove character at index
Reverse	(string)	Reverse the string
UppercaseFirst	(string)	Capitalize first character
UUID	()	Generate RFC4122 v4 UUID string

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Common Patterns

Using Actions with Groups

const enemies = this.add.group({ key: 'enemy', repeat: 9 });

// Position all children in a grid
Phaser.Actions.GridAlign(enemies.getChildren(), {
    width: 5, height: 2,
    cellWidth: 80, cellHeight: 80,
    x: 100, y: 50
});

// Fan out alpha across all enemies
Phaser.Actions.Spread(enemies.getChildren(), 'alpha', 0.3, 1);

Step Parameter for Staggered Values

// Place sprites starting at x=100, each one 50px further right
Phaser.Actions.SetX(sprites, 100, 50);
// Result: items[0].x=100, items[1].x=150, items[2].x=200, ...

// Increment rotation with increasing step
Phaser.Actions.Rotate(sprites, 0.1, 0.05);
// Result: items[0].rotation += 0.1, items[1].rotation += 0.15, items[2].rotation += 0.2, ...

Scatter Then Constrain

const bounds = new Phaser.Geom.Rectangle(0, 0, 800, 600);
// Random scatter
Phaser.Actions.RandomRectangle(sprites, bounds);
// Keep wrapped in bounds during update
Phaser.Actions.WrapInRectangle(sprites, bounds);

GetValue for Config Parsing

// Deep property access with fallback
const width = Phaser.Utils.Objects.GetValue(config, 'render.screen.width', 800);

// Fast top-level lookup (no dot-path, better performance)
const speed = Phaser.Utils.Objects.GetFastValue(config, 'speed', 100);

NumberArray for Asset Keys

// Generate frame key strings
const keys = Phaser.Utils.Array.NumberArray(1, 10, 'frame_', '.png');
// Result: ['frame_1.png', 'frame_2.png', ..., 'frame_10.png']

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Gotchas

• Actions operate on plain arrays, not Groups directly. Always call group.getChildren() to get the array.
• PlaceOn/Random geometry actions need Phaser.Geom objects, not Game Object shapes. For a Phaser.GameObjects.Circle, pass circle.geom.
• SetXY defaults y to x if y is undefined or null. Pass 0 explicitly if you want y=0 and x=something else.
• Spread with a single item places it at the midpoint (min + max) / 2, not at min.
• step is multiplied by iteration index, not added cumulatively. Item 0 gets value + 0*step, item 1 gets value + 1*step, etc.
• StableSort uses native Array.sort when the engine supports stable sorting, falling back to merge sort only when needed.
• Shuffle (both Actions and Utils.Array) modifies the array in-place and returns it.
• GetValue vs GetFastValue: Use GetFastValue when the key is always top-level (no dots). It skips dot-path parsing and is faster in hot loops.
• AddEffectBloom / AddEffectShine / AddMaskShape are v4-only filter-based effects. They return arrays of created effects instead of the input.

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Source File Map

Area	Path
All Actions	src/actions/
Actions index	src/actions/index.js
Core set/inc helpers	src/actions/PropertyValueSet.js, src/actions/PropertyValueInc.js
GridAlign config typedef	src/actions/typedefs/
Array utilities	src/utils/array/
Array matrix utils	src/utils/array/matrix/
Object utilities	src/utils/object/
String utilities	src/utils/string/