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tap()

tap<T>(tapper): OperatorFunction<T, T>

Defined in: src/Tap.ts:27

Creates an operator that calls tapper for every item and passes the item through unchanged. An asynchronous tapper is awaited before the item is passed on.

Type Parameters​

T​

T

Parameters​

tapper​

(input) => void | Promise<void>

a side effect to run for every item

Returns​

OperatorFunction<T, T>

an operator function

Example​

const log: string[] = [];
const result = await chain(["a", "b"])
    .tap((s) => {
        log.push(`saw ${s}`);
    })
    .onEnd(() => {
        log.push("done");
    })
    .toArray();
// result => ["a", "b"]
// log => ["saw a", "saw b", "done"]