Goroutines in JavaScript

A goroutine is a lightweight thread of execution.

function f(from) {
    for (let i = 0; i < 3; i++) {
        console.log(from + " :", i);
    }
}

function main() {
    // Suppose we have a function call `f(s)`. Here’s how
    // we’d call that in the usual way, running it
    // synchronously.
    f("direct");

    // To invoke this function in a goroutine, use
    // `go f(s)`. This new goroutine will execute
    // concurrently with the calling one.
    setTimeout(() => f("goroutine"), 0);

    // You can also start a goroutine for an anonymous
    // function call.
    setTimeout(() => console.log("going"), 0);

    // Our two function calls are running asynchronously in
    // separate goroutines now. Wait for them to finish
    // (for a more robust approach, use a WaitGroup).
    setTimeout(() => console.log("done"), 1000);
}

main();

When we run this program, we see the output of the blocking call first, then the output of the two goroutines. The goroutines’ output may be interleaved, because goroutines are being run concurrently by the runtime.

$ node example.js
direct : 0
direct : 1
direct : 2
goroutine : 0
going
goroutine : 1
goroutine : 2
done

Next we’ll look at a complement to goroutines in concurrent programs: channels.

Custom Errors in JavaScript

Channels in JavaScript

Learn X By Example

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Goroutines in JavaScript