Let's look at an example:
This is what happens in the example given above:
- The JavaScript engine prints
Hello to the console.
- When the JavaScript engine encounters
searchOnGoogle("Learn Javascript"),
it tries to search on Google. If Google is slow that day,
JavaScript just waits for the results, not doing anything else,
even though it could be doing something useful.
This effectively blocks the execution of the program.
- Only after the search operation completes
does the JavaScript engine print
Hi to the console.
With asynchronous code, the JavaScript engine could have
initiated the search operation and concurrently
executed other tasks while waiting for the search results.