Download and extract protoc-gen.js and configure it

build.gradle.kts

import com.google.protobuf.gradle.id
import de.undercouch.gradle.tasks.download.Download
import org.gradle.nativeplatform.platform.internal.DefaultNativePlatform

plugins {
    id("java")
    id("idea")
    id("net.linguica.maven-settings") version "0.5"
    `maven-publish`
    id("com.google.protobuf") version "0.9.3"
    id("de.undercouch.download") version "5.4.0"

}
val protocGenJsVersion = "3.21.2"
val protocjsDir = "${projectDir}/protocjs" 

val downloadAndUnzipFile = tasks.register<Copy>("downloadAndUnzipFile") {
    dependsOn(downloadZip)
    from(zipTree(downloadZip.get().dest))
    into(protocjsDir)
    fileMode = "755".toInt(radix = 8) // kotlin does not support oktals
}

val downloadZip = tasks.register<Download>("downloadZipFile") {
    val os = DefaultNativePlatform.getCurrentOperatingSystem()
    val arch = DefaultNativePlatform.getCurrentArchitecture();
    var downloadOsName = "linux"
    if (os.isWindows) {
        downloadOsName = "win64"
    }
    if (os.isMacOsX) {
        downloadOsName = "osx"
        if (arch.isArm) {
            downloadOsName += "-aarch_64"
        }
    }
    if (os.isLinux) {
        downloadOsName = "linux"
        if (arch.isAmd64) {
            downloadOsName += "-x86_64"
        }
        if (arch.isArm) {
            downloadOsName += "-aarch64"
        }
    }
    print("downloadOsName $downloadOsName")
    val downloadSrc =
        "https://github.com/protocolbuffers/protobuf-javascript/releases/download/v${protocGenJsVersion}/protobuf-javascript-${protocGenJsVersion}-${downloadOsName}.zip"
    src(downloadSrc)
    dest(File(protocjsDir, "protobuf-javascript-${protocGenJsVersion}-${downloadOsName}.zip"))

}
 // Configure the protoc executable
    protoc {
        // Download from repositories
        artifact = "com.google.protobuf:protoc:3.23.0"
    }
    plugins {
        id("grpc") {
            artifact = "io.grpc:protoc-gen-grpc-java:1.55.1"
            // or
            // path = 'tools/protoc-gen-grpc-java'
        }

        id("js") {
            path = "$protocjsDir/bin/protoc-gen-js"
            if (DefaultNativePlatform.getCurrentOperatingSystem().isWindows) {
                path += ".exe"
            }
        }
    }
    generateProtoTasks {
        ofSourceSet("main").forEach {

            all().configureEach {
                dependsOn(downloadAndUnzipFile)
            }

            it.plugins {
                // Apply the "grpc" plugin whose spec is defined above, without
                // options. Note the braces cannot be omitted, otherwise the
                // plugin will not be added. This is because of the implicit way
                // NamedDomainObjectContainer binds the methods.
                id("grpc") { }

                id("js") {
                    option("import_style=closure")
                    option("binary")
                    option("library=fxl_proto_library")
                }
            }
        }