How to use addExtraLib in Monaco with an external type definition

monaco-editor

I can see how to use addExtraLib in Monaco to add an ambient declaration file. What's not clear is how to use this function with an external declaration file so that Typescript code in the editor can do a:

import * as External from "external" 
    
External.foo();

On the Monaco set-up side, this doesn't seem to work:

 // compiler options
monaco.languages.typescript.typescriptDefaults.setCompilerOptions({
    target: monaco.languages.typescript.ScriptTarget.ES2016,
    allowNonTsExtensions: true,
    moduleResolution: monaco.languages.typescript.ModuleResolutionKind.NodeJs,
    module: monaco.languages.typescript.ModuleKind.CommonJS,
    noEmit: true,
    noLib: true,
    typeRoots: ["node_modules/@types"]
});

// extra libraries
monaco.languages.typescript.typescriptDefaults.addExtraLib(
    'export declare function foo():string;', 'node_modules/@types/external/index.d.ts');

monaco.languages.typescript.typescriptDefaults.setDiagnosticsOptions({
    noSemanticValidation: false,
    noSyntaxValidation: false

After playing around a little I found a solution. Basically, the file has to be loaded using createModel with an explicit file URL. If you do this then the relative file path for node_module/@types works. Here's my working solution that can be used in the playground:

// compiler options
monaco.languages.typescript.typescriptDefaults.setCompilerOptions({
    target: monaco.languages.typescript.ScriptTarget.ES2016,
    allowNonTsExtensions: true,
    moduleResolution: monaco.languages.typescript.ModuleResolutionKind.NodeJs,
    module: monaco.languages.typescript.ModuleKind.CommonJS,
    noEmit: true,
    typeRoots: ["node_modules/@types"]
});

// extra libraries
monaco.languages.typescript.typescriptDefaults.addExtraLib(
    `export declare function next() : string`,
    'node_modules/@types/external/index.d.ts');

monaco.languages.typescript.typescriptDefaults.setDiagnosticsOptions({
    noSemanticValidation: false,
    noSyntaxValidation: false
})

var jsCode = `import * as x from "external"
    const tt : string = x.dnext();`;

monaco.editor.create(document.getElementById("container"), {
    model: monaco.editor.createModel(jsCode,"typescript",new monaco.Uri("file:///main.tsx")), 
});

Joe's answer didn't work for me, fixed by prefixing the external type definition file path with file:///

Here's an updated example for the playground:

monaco.languages.typescript.typescriptDefaults.addExtraLib(
    'export declare function add(a: number, b: number): number',
    'file:///node_modules/@types/math/index.d.ts'
);

const model = monaco.editor.createModel(
    `import {add} from 'math';\nconst x = add(3, 5);\n`,
    'typescript',
    monaco.Uri.parse('file:///main.tsx')
);

monaco.editor.create(document.getElementById('container'), {model});

It's not necessary to provide the compiler options and diagnostic options.

How to use addExtraLib in Monaco with an external type definition

Related

Recent Posts