Utilities

LittleJS Utility Classes and Functions

  • General purpose math library
  • Vector2 - fast, simple, easy 2D vector class
  • Color - holds a rgba color with some math functions
  • Timer - tracks time automatically
  • RandomGenerator - seeded random number generator
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Members

(static, constant) BLACK :Color

Color - Black #000000

Type:
  • Color
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(static, constant) BLUE :Color

Color - Blue #0000ff

Type:
  • Color
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(static, constant) CLEAR_BLACK :Color

Color - Clear Black #000000 with 0 alpha

Type:
  • Color
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(static, constant) CLEAR_WHITE :Color

Color - Clear White #757474ff with 0 alpha

Type:
  • Color
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(static, constant) CYAN :Color

Color - Cyan #00ffff

Type:
  • Color
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(static, constant) GRAY :Color

Color - Gray #808080

Type:
  • Color
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(static, constant) GREEN :Color

Color - Green #00ff00

Type:
  • Color
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(static, constant) MAGENTA :Color

Color - Magenta #ff00ff

Type:
  • Color
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(static, constant) ORANGE :Color

Color - Orange #ff8000

Type:
  • Color
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(static, constant) PI :number

The value of PI

Type:
  • number
Default Value
  • Math.PI
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(static, constant) PURPLE :Color

Color - Purple #8000ff

Type:
  • Color
Source

(static, constant) RED :Color

Color - Red #ff0000

Type:
  • Color
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(static, constant) WHITE :Color

Color - White #ffffff

Type:
  • Color
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(static, constant) YELLOW :Color

Color - Yellow #ffff00

Type:
  • Color
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(static, constant) abs

Returns absolute value of value passed in

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(static, constant) atan2

Returns atan2 of values passed in

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(static, constant) ceil

Returns ceiled value of value passed in

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(static, constant) cos

Returns cos of value passed in

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(static, constant) floor

Returns floored value of value passed in

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(static, constant) hypot

Returns hypotenuse of values passed in

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(static, constant) log2

Returns log2 of value passed in

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(static, constant) max

Returns highest value passed in

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(static, constant) min

Returns lowest value passed in

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(static, constant) round

Returns rounded value passed in

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(static, constant) sign

Returns the sign of value passed in

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(static, constant) sin

Returns sin of value passed in

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(static, constant) tan

Returns tan of value passed in

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Methods

(static) clamp(value, minopt, maxopt) → {number}

Clamps the value between max and min

Parameters:
NameTypeAttributesDefaultDescription
valuenumber
minnumber<optional>
0
maxnumber<optional>
1
Source
Returns:
Type: 
number

(static) distanceAngle(angleA, angleB) → {number}

Returns signed wrapped distance between the two angles passed in

Parameters:
NameTypeDescription
angleAnumber
angleBnumber
Source
Returns:
Type: 
number

(static) distanceWrap(valueA, valueB, wrapSizeopt) → {number}

Returns signed wrapped distance between the two values passed in

Parameters:
NameTypeAttributesDefaultDescription
valueAnumber
valueBnumber
wrapSizenumber<optional>
1
Source
Returns:
Type: 
number

(async, static) fetchJSON(url) → {Promise.<object>}

Fetches a JSON file from a URL and returns the parsed JSON object. Must be used with await!

Parameters:
NameTypeDescription
urlstring

URL of JSON file

Source
Returns:
Type: 
Promise.<object>

(static) formatTime(t) → {string}

Formats seconds to mm:ss style for display purposes

Parameters:
NameTypeDescription
tnumber

time in seconds

Source
Returns:
Type: 
string

(static) hsl(hopt, sopt, lopt, aopt) → {Color}

Create a color object with HSLA values, white by default

Parameters:
NameTypeAttributesDefaultDescription
hnumber<optional>
0

hue

snumber<optional>
0

saturation

lnumber<optional>
1

lightness

anumber<optional>
1

alpha

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Returns:
Type: 
Color

(static) isArray(a) → {boolean}

Check if object is an array

Parameters:
NameTypeDescription
aany
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Returns:
Type: 
boolean

(static) isColor(c) → {boolean}

Check if object is a valid Color

Parameters:
NameTypeDescription
cany
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Returns:
Type: 
boolean

(static) isIntersecting(start, end, pos, size) → {boolean}

Returns true if a line segment is intersecting an axis aligned box

Parameters:
NameTypeDescription
startVector2

Start of raycast

endVector2

End of raycast

posVector2

Center of box

sizeVector2

Size of box

Source
Returns:
  • True if intersecting
Type: 
boolean

(static) isNumber(n) → {boolean}

Check if object is a valid number, not NaN or undefined, but it may be infinite

Parameters:
NameTypeDescription
nany
Source
Returns:
Type: 
boolean

(static) isOverlapping(posA, sizeA, posB, sizeBopt) → {boolean}

Returns true if two axis aligned bounding boxes are overlapping this can be used for simple collision detection between objects

Parameters:
NameTypeAttributesDefaultDescription
posAVector2

Center of box A

sizeAVector2

Size of box A

posBVector2

Center of box B

sizeBVector2<optional>
(0,0)

Size of box B, uses a point if undefined

Source
Returns:
  • True if overlapping
Type: 
boolean

(static) isPowerOfTwo(value) → {boolean}

Checks if the value passed in is a power of two

Parameters:
NameTypeDescription
valuenumber
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Returns:
Type: 
boolean

(static) isString(s) → {boolean}

Check if object is a valid string or can be converted to one

Parameters:
NameTypeDescription
sany
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Returns:
Type: 
boolean

(static) isVector2(v) → {boolean}

Check if object is a valid Vector2

Parameters:
NameTypeDescription
vany
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Returns:
Type: 
boolean

(static) lerp(valueA, valueB, percent) → {number}

Linearly interpolates between values passed in using percent

Parameters:
NameTypeDescription
valueAnumber
valueBnumber
percentnumber
Source
Returns:
Type: 
number

(static) lerpAngle(angleA, angleB, percent) → {number}

Linearly interpolates between the angles passed in with wrapping

Parameters:
NameTypeDescription
angleAnumber
angleBnumber
percentnumber
Source
Returns:
Type: 
number

(static) lerpWrap(valueA, valueB, percent, wrapSizeopt) → {number}

Linearly interpolates between values passed in with wrapping

Parameters:
NameTypeAttributesDefaultDescription
valueAnumber
valueBnumber
percentnumber
wrapSizenumber<optional>
1
Source
Returns:
Type: 
number

(static) lineTest(posStart, posEnd, testFunction, normalopt) → {Vector2|undefined}

Casts a ray and returns position of the first collision found, or undefined if none are found

Parameters:
NameTypeAttributesDescription
posStartVector2
posEndVector2
testFunctionLineTestFunction

Check if colliding

normalVector2<optional>

Optional vector to store the normal

Source
Returns:
  • Position of the collision or undefined if none found
Type: 
Vector2 | undefined

(static) mod(dividend, divisoropt) → {number}

Returns first parm modulo the second param, but adjusted so negative numbers work as expected

Parameters:
NameTypeAttributesDefaultDescription
dividendnumber
divisornumber<optional>
1
Source
Returns:
Type: 
number

(static) nearestPowerOfTwo(value) → {number}

Returns the nearest power of two not less than the value

Parameters:
NameTypeDescription
valuenumber
Source
Returns:
Type: 
number

(static) percent(value, valueA, valueB) → {number}

Returns what percentage the value is between valueA and valueB

Parameters:
NameTypeDescription
valuenumber
valueAnumber
valueBnumber
Source
Returns:
Type: 
number

(static) percentLerp(value, percentA, percentB, lerpA, lerpB) → {number}

Gets percent between percentA and percentB and linearly interpolates between lerpA and lerpB A shortcut for lerp(lerpA, lerpB, percent(value, percentA, percentB))

Parameters:
NameTypeDescription
valuenumber
percentAnumber
percentBnumber
lerpAnumber
lerpBnumber
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Returns:
Type: 
number

(static) rgb(ropt, gopt, bopt, aopt) → {Color}

Create a color object with RGBA values, white by default

Parameters:
NameTypeAttributesDefaultDescription
rnumber<optional>
1

red

gnumber<optional>
1

green

bnumber<optional>
1

blue

anumber<optional>
1

alpha

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Returns:
Type: 
Color

(static) smoothStep(percent) → {number}

Applies smoothstep function to the percentage value

Parameters:
NameTypeDescription
percentnumber
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Returns:
Type: 
number

(static) vec2(xopt, yopt) → {Vector2}

Create a 2d vector, can take 1 or 2 scalar values

Parameters:
NameTypeAttributesDefaultDescription
xnumber<optional>
0
ynumber<optional>

if y is undefined, x is used for both

Source
Returns:
Type: 
Vector2
Example
let a = vec2(0, 1); // vector with coordinates (0, 1)
a = vec2(5);        // set a to (5, 5)
b = vec2();         // set b to (0, 0)

(static) wave(frequencyopt, amplitudeopt, topt, offsetopt) → {number}

Returns an oscillating wave between 0 and amplitude with frequency of 1 Hz by default

Parameters:
NameTypeAttributesDefaultDescription
frequencynumber<optional>
1

Frequency of the wave in Hz

amplitudenumber<optional>
1

Amplitude (max height) of the wave

tnumber<optional>
time

Value to use for time of the wave

offsetnumber<optional>
0

Value to use for time offset of the wave

Source
Returns:
  • Value waving between 0 and amplitude
Type: 
number