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Contents
/**
* Applies an accumulator function over an observable sequence and returns each intermediate result. The optional seed value is used as the initial accumulator value.
* For aggregation behavior with no intermediate results, see Observable.aggregate.
* @example
* var res = source.scan(function (acc, x) { return acc + x; });
* var res = source.scan(0, function (acc, x) { return acc + x; });
* @param {Mixed} [seed] The initial accumulator value.
* @param {Function} accumulator An accumulator function to be invoked on each element.
* @returns {Observable} An observable sequence containing the accumulated values.
*/
observableProto.scan = function () {
var hasSeed = false, seed, accumulator, source = this;
if (arguments.length === 2) {
hasSeed = true;
seed = arguments[0];
accumulator = arguments[1];
} else {
accumulator = arguments[0];
}
return new AnonymousObservable(function (o) {
var hasAccumulation, accumulation, hasValue;
return source.subscribe (
function (x) {
!hasValue && (hasValue = true);
try {
if (hasAccumulation) {
accumulation = accumulator(accumulation, x);
} else {
accumulation = hasSeed ? accumulator(seed, x) : x;
hasAccumulation = true;
}
} catch (e) {
o.onError(e);
return;
}
o.onNext(accumulation);
},
function (e) { o.onError(e); },
function () {
!hasValue && hasSeed && o.onNext(seed);
o.onCompleted();
}
);
}, source);
};
Version data entries
14 entries across 7 versions & 1 rubygems