[Lodash] static var not working anymore

[farfromrefug]

With the latest typings for lodash i can't use the static declare of _

My project do not "import" lodash anywhere but it is available still.
For me the typings were working before thanks to:

declare var _: _.LoDashStatic;

But now there is some export so the declare is only in the scope of the module.
Is that on purpose?

An easy way to fix it if not on purpose is to replace:

declare var _: _.LoDashStatic;

with

declare global {
    var _: _.LoDashStatic;
}

[ghost]

export as namespace _; should be declaring the global variable you need. What's the precise error you're getting?

[farfromrefug]

@andy-ms no it won't declare it as global outside of the module. At least not for me.
I think it is because of export = _; which makes it a module declaration. And by such to augmente the global scope you need to use declare global

But it might be the right way to go by not declaring _ in global and instead expect import * as _ from 'lodash'
I need my case i found a solution by creating a lodash.d.ts in my project with this

import * as _ from 'lodash'

declare global{
    var _:_.LoDashStatic & {
        remove<T, K extends keyof T>(
            object: T,
            key?: K,
            defaultValue?: T[K]
        ): T[K]
        getKeyByValue(object, value)
        mapIfDefined(array, func)
        mod(n, m)
        move(array, oldIndex, newIndex)
        pick<T, K extends keyof T>(obj: T, ...keys: K[]): Pick<T, K>
    }
}

As you can see it also shows how to extend lodash definitions.

I won't close it until you decide if it's a normal behavior now for lodash not to extend global scope.

[ghost]

Can you provide an example project that reproduces the error?

[farfromrefug]

@andy-ms I think a default project with lodash package installed but not imported would suffise.

[ghost]

No, that works just fine for me.

[farfromrefug]

can you try with that tsconfig.json

{
    "compilerOptions": {
        "target": "es6",
        "moduleResolution": "node",
        "module": "commonjs",
        "preserveConstEnums": true,
        "declaration": true,
        "noImplicitAny": false,
        "removeComments": true,
        "noLib": false,
        "sourceMap": true,
        "experimentalDecorators": true,
        "emitDecoratorMetadata": true,
        "noImplicitUseStrict": true
    },
    "include": [
          "Resources/**/*.ts"
      ]
}

Just change the "include"

[ghost]

That works for me if I npm install @types/lodash and put the text _.add(1, 2); in Resources/a.ts.

[farfromrefug]

Ok this is really weird. By moving things i got the same result as you.
My error might be that i try to extend LodashStatic
How would extend LodashStatic to add mixins functions definitions?

Thanks

[ghost]

I think that issue is microsoft/TypeScript#17736.

[farfromrefug]

@andy-ms thanks. Can we keep this open until there is a solution?

[ghost]

OK

[farfromrefug]

OK so after seeing the discussion in the issue you referenced i found a way to go it to work all the time for me.

First let me explain why it worked for you and not for me.
It worked for you because in the example file were not doing any import. Add an import and the global _ won't work.

Now what i did to get _ everywhere and to augment it i created a lodash.d.ts file in my project:

declare module "mod" {
    module "lodash" {
        interface LoDashStatic {
            remove<T, K extends keyof T>(
                object: T,
                key?: K,
                defaultValue?: T[K]
            ): T[K]
            getKeyByValue(object, value)
            mapIfDefined(array, func)
            mod(n, m)
            move(array, oldIndex, newIndex)
            pick<T, K extends keyof T>(obj: T, ...keys: K[]): Pick<T, K>
        }
    }
}
declare var _: _.LoDashStatic;

Now i get global _ everywhere with my mixins