syscall/js: Wasm build in docker resulted in error gojs error is not object or function

[sujit-baniya]

What version of Go are you using (go version)?

1.21

$ go version

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

Linux Intel and Mac Silicon

go env Output

$ go env

What did you do?

I tried to build the wasm binary in Dockerfile to be used by React frontend. For the purpose I build a Dockerfile with following content.

FROM golang:alpine as go
WORKDIR /app
COPY ./wasm .
RUN go mod tidy && GOOS=js GOARCH=wasm go build -ldflags="-w -s" -o main.wasm

FROM node:alpine as web
RUN npm install -g pnpm
WORKDIR /app
COPY package.json .
COPY package-lock.json .
RUN pnpm install
COPY . .
RUN pnpm build:ts

FROM nginx:latest
WORKDIR /usr/share/nginx/html
RUN rm -rf ./*
COPY --from=web /app/build .
COPY --from=go /app/main.wasm .
ENTRYPOINT ["nginx", "-g", "daemon off;"]

Resource: https://github.com/sujit-baniya/react-app-typescript-golang/blob/master/Dockerfile

Then running the commands

docker compose build && docker compose up -d

What did you expect to see?

I expected to see the working version of application and don't see any error.

What did you see instead?

I see error on browser when visiting the application on browser

Uncaught (in promise) TypeError: WebAssembly.instantiate(): Import #0 module="gojs" error: module is not an object or function

[seankhliao]

your wasm_exec.js doesn't line up with the one we distribute https://github.com/golang/go/blob/go1.21.0/misc/wasm/wasm_exec.js#L216

[sujit-baniya]

@seankhliao Can we move this to discussion as it's throwing error on following:

src/LoadWasm/wasm_exec.js
  Line 14:8:    'globalThis' is not defined  no-undef
  Line 16:5:    'globalThis' is not defined  no-undef
  Line 61:8:    'globalThis' is not defined  no-undef
  Line 62:5:    'globalThis' is not defined  no-undef
  Line 76:8:    'globalThis' is not defined  no-undef
  Line 80:8:    'globalThis' is not defined  no-undef
  Line 84:8:    'globalThis' is not defined  no-undef
  Line 88:8:    'globalThis' is not defined  no-undef
  Line 95:3:    'globalThis' is not defined  no-undef
  Line 241:13:  'fs' is not defined          no-undef
  Line 477:9:   'globalThis' is not defined  no-undef
  Line 486:10:  'globalThis' is not defined  no-undef

Search for the keywords to learn more about each error.

I added const globalThis = window; on the top but it still failing on

[eslint] 
src/LoadWasm/wasm_exec.js
  Line 241:13:  'fs' is not defined  no-undef

Search for the keywords to learn more about each error.

[sujit-baniya]

Got it working with some small changes in https://github.com/golang/go/blob/go1.21.0/misc/wasm/wasm_exec.js

https://github.com/sujit-baniya/react-app-typescript-golang/blob/master/src/LoadWasm/wasm_exec.js

Changes:

1. Added const globalThis = window; https://github.com/sujit-baniya/react-app-typescript-golang/blob/master/src/LoadWasm/wasm_exec.js#L7
2. Changed fs.writeSync to globalThis.fs.writeSync https://github.com/sujit-baniya/react-app-typescript-golang/blob/master/src/LoadWasm/wasm_exec.js#L242