error TS2304: Cannot find name 'WebAssembly'

Question

I probably have a TypeScript configuration issue but for the life of me I can't figure it out. I am running in nodejs v11 and using TypeScript v3.4.5.

I am simply attempting to compile the following code with typescript:

const { Module, Instance } = WebAssembly;

Which generates the error:

error TS2304: Cannot find name 'WebAssembly'.

What's strange is if I hover over all 3 types in VSCode it properly resolves the Types and shows me no errors.

If I use this workaround, it compiles and runs successfully:

const { Module, Instance } = (global as any).WebAssembly;

What do I have to do to get TS to recognize WebAssembly correctly?

Here is my current tsconfig.json file:

{
    "compilerOptions": {
      "inlineSourceMap": true,
      "noUnusedLocals": true,
      "outDir": "build",
      "target":"es2018",
      "experimentalDecorators": true,
      "emitDecoratorMetadata": true,
      "esModuleInterop": true,
      "module": "commonjs",
      "moduleResolution": "node",
      "noUnusedParameters": false

    },
    "exclude": ["node_modules"],
    "include": ["src/**/*.ts"]
  }

EDIT: It works with this config:

{
  "compilerOptions": {
    "removeComments": true,
    "sourceMap": true,
    "target": "es6",
    "module":"commonjs",
    "moduleResolution": "node",
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "lib": ["es2018", "dom"],
    "outDir": "build",
    "sourceRoot": "src",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true
  },
  "include": ["**/*.ts"],
  "exclude": ["**/node_modules"]
}

I have the same problem. Some advice to add "lib": [ "dom" ] to compilerOptions, but it didn't work for me. — Tony I.
– Tony I., Commented Jul 29, 2019 at 16:02
Yeah that did seem to fix it. I'll update the question with a working config, and if it fixes it for you you can submit answer and I'll mark it as the right answer. — justin.m.chase
– justin.m.chase, Commented Jul 30, 2019 at 22:35
With this config I now get Property 'instantiateStreaming' does not exist on type 'typeof WebAssembly'. — Tony I.
– Tony I., Commented Aug 2, 2019 at 15:18
It looks like that function isn't available in nodejs yet. Perhaps remove the "es2018" from "lib"? I'm not sure. — justin.m.chase
– justin.m.chase, Commented Aug 2, 2019 at 19:14

Jorge Leitao · Accepted Answer · 2021-11-02 16:35:11Z

2

This happens because the type declarations for webassembly are only available from typescript >3.4, as per this comment.

The solution is to bump typescript to at least 3.6(?)

edited Nov 2, 2021 at 16:35

answered Oct 22, 2021 at 12:40

Jorge Leitao

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EuberDeveloper · Accepted Answer · 2024-08-15 17:55:04Z

1

Just an addition, in my case the typescript's version was much newer than 3.6 (namely 5.5.4), but I still was having the issue "error TS2503: Cannot find namespace 'WebAssembly"

The solution, as per this GH issue, was adding DOM to the compilerOptions.lib parameter of tsconfig.json

answered Aug 15, 2024 at 17:55

EuberDeveloper

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