const tasks = of([....]);
/**
* {
* ...{ ...4......5......2}
* ...........{3...........2...5}
* ..................................{6.... 3}
* ..........................................{3..4....2}
* }
*
*/
const animationAllowed = tasks
.map((task) =>
// preappend 1
// append -1
// ingore task
Observable.concat(
of(1), //start
task.filter(() => false),
of(-1) //end
)
)
/**
* {
* ...{1................-1}
* ...........{1................-1}
* ...................................{1.......-1}
* ..........................................{1......-1}
* }
*
*/
.mergeAll()
// {....1....1.........-1........-1....1.....1.-1....-1}
.scan((acc, curr) => {
return acc + curr;
}, 0)
// {....1....2........1..........0.....1.....2.1......0}
.map((num) => {
return num === 0;
})
// {....F......F..........F......T..... F......F.F....T}
.distincTUntilChanged();
// {....F........................T..... F.............T}