Fix: don't call useTransition's update lifecycle if items are the same

.npmignore

@@ -0,0 +1 @@
+dist/__tests__

package.json

@@ -18,7 +18,7 @@
     "test": "jest",
     "test:dev": "jest --watch --no-coverage",
     "test:coverage:watch": "jest --watch",
-    "test:ts": "tsc --noEmit",
+    "test:ts": "tsc -p types/__tests__/tsconfig.json",
     "postinstall": "node -e \"console.log('\\u001b[35m\\u001b[1mEnjoy react-spring? You can now donate to our open collective:\\u001b[22m\\u001b[39m\\n > \\u001b[34mhttps://opencollective.com/react-spring/donate\\u001b[0m')\""
   },
   "husky": {
@@ -97,6 +97,7 @@
     "rollup-plugin-node-resolve": "4.0.0",
     "rollup-plugin-size-snapshot": "0.8.0",
     "rollup-plugin-uglify": "6.0.2",
+    "spec.ts": "^1.1.0",
     "typescript": "3.3.3"
   },
   "peerDependencies": {

src/animated/AnimatedInterpolation.ts

@@ -43,6 +43,6 @@ export default class AnimatedInterpolation extends AnimatedArray<Animated>
     range: number[] | InterpolationConfig | ((...args: any[]) => IpValue),
     output?: (number | string)[]
   ): AnimatedInterpolation {
-    return new AnimatedInterpolation(this, range as number[], output!)
+    return new AnimatedInterpolation(this, range as number[], output)
   }
 }

src/animated/AnimatedValue.ts

@@ -3,6 +3,7 @@ import { InterpolationConfig } from '../types/interpolation'
 import Animated from './Animated'
 import AnimatedInterpolation from './AnimatedInterpolation'
 import AnimatedProps from './AnimatedProps'
+import { now } from './Globals'
 
 /**
  * Animated works by building a directed acyclic graph of dependencies
@@ -41,15 +42,15 @@ function addAnimatedStyles(
 export default class AnimatedValue extends Animated implements SpringValue {
   private animatedStyles = new Set<AnimatedProps>()
 
-  public value: number | string
-  public startPosition: number | string
-  public lastPosition: number | string
+  public value: any
+  public startPosition: any
+  public lastPosition: any
   public lastVelocity?: number
   public startTime?: number
   public lastTime?: number
   public done = false
 
-  constructor(value: number | string) {
+  constructor(value: any) {
     super()
     this.value = value
     this.startPosition = value
@@ -67,7 +68,7 @@ export default class AnimatedValue extends Animated implements SpringValue {
     this.animatedStyles.clear()
   }
 
-  public setValue = (value: number | string, flush = true) => {
+  public setValue = (value: any, flush = true) => {
     this.value = value
     if (flush) this.flush()
   }
@@ -82,4 +83,14 @@ export default class AnimatedValue extends Animated implements SpringValue {
   ): AnimatedInterpolation {
     return new AnimatedInterpolation(this, range as number[], output!)
   }
+
+  public reset(isActive: boolean) {
+    this.startPosition = this.value
+    this.lastPosition = this.value
+    this.lastVelocity = isActive ? this.lastVelocity : undefined
+    this.lastTime = isActive ? this.lastTime : undefined
+    this.startTime = now()
+    this.done = false
+    this.animatedStyles.clear()
+  }
 }

src/animated/AnimatedValueArray.ts

@@ -6,12 +6,12 @@ import AnimatedValue from './AnimatedValue'
 
 export default class AnimatedValueArray extends AnimatedArray<AnimatedValue>
   implements SpringValue {
-  constructor(values: (string | number)[]) {
+  constructor(values: AnimatedValue[]) {
     super()
-    this.payload = values.map(n => new AnimatedValue(n))
+    this.payload = values
   }
 
-  public setValue(value: (string | number)[] | string | number, flush = true) {
+  public setValue(value: any, flush = true) {
     if (Array.isArray(value)) {
       if (value.length === this.payload.length) {
         value.forEach((v, i) => this.payload[i].setValue(v, flush))
@@ -29,6 +29,6 @@ export default class AnimatedValueArray extends AnimatedArray<AnimatedValue>
     range: number[] | InterpolationConfig | ((...args: any[]) => any),
     output?: (number | string)[]
   ): AnimatedInterpolation {
-    return new AnimatedInterpolation(this, range as number[], output!)
+    return new AnimatedInterpolation(this, range as number[], output)
   }
 }