(f: (a: A[K]) => void)
| 252 | return this.previous |
| 253 | } |
| 254 | subscribe(f: (a: A[K]) => void): () => void { |
| 255 | let previous = this.value |
| 256 | return this.parent.subscribe((a) => { |
| 257 | if (!a || !(this._prop in (a as any))) { |
| 258 | return |
| 259 | } |
| 260 | const next = a[this._prop] |
| 261 | if (Equal.equals(next, previous)) { |
| 262 | return |
| 263 | } |
| 264 | previous = next |
| 265 | f(next) |
| 266 | }) |
| 267 | } |
| 268 | map<C>(f: (a: A[K]) => C): ReadonlyRef<C> { |
| 269 | return new MapRefImpl(this, f) |
| 270 | } |