RxJS mergeMap vs concatMap vs switchMap - gecko-8/devwiki GitHub Wiki

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All three:

• Are used in the pipe on a single source observable
• Allow interaction with a second (inner) observable
• Result in a new observable based on the original two

concatMap

• Subscribe to observables in sequence, processing each in it's entirety before moving on to the next

mergeMap

• Processes each observable in it's entirety but interleaves the results based on when the value was received

switchMap

• Similar to mergeMap but inner observables are cancelled as soon as a new value is received from the outer observable