TypeScript 3.7.5 error in the strict mode inside addQueryParams method

private addQueryParams(query: object): string {
    const keys = Object.keys(query);
    return keys.length ? (
      '?' +
      keys.reduce((paramsArray, param) => [
        ...paramsArray,
        param + '=' + encodeURIComponent(query[param])
      ], []).join('&')
    ) : ''
  }

src/templates/client.mustache

(parameter) param: string No overload matches this call. Overload 1 of 3, ‘(callbackfn: (previousValue: string, currentValue: string, currentIndex: number, array: string[]) => string, initialValue: string): string’, gave the following error. Type ‘string[]’ is not assignable to type ‘string’. Overload 2 of 3, ‘(callbackfn: (previousValue: never[], currentValue: string, currentIndex: number, array: string[]) => never[], initialValue: never[]): never[]’, gave the following error. Type ‘string[]’ is not assignable to type ‘never[]’. Type ‘string’ is not assignable to type ‘never’.ts(2769) lib.es5.d.ts(1350, 24): The expected type comes from the return type of this signature. lib.es5.d.ts(1356, 27): The expected type comes from the return type of this signature.

I suggest following code:

  private addQueryParams(query: {[key:string]:string|number|boolean}): string {
    const keys = Object.keys(query);
    return keys.length === 0 ? ''
      : '?' + keys.map(key => encodeURIComponent(key) + '=' + encodeURIComponent(query[key])).join('&')
  }

[js2me]

@genaby as this is Api module which do requests to the server. I think needs to do more flexible solution for developers usage.
input type queries sometimes will have { optionalKey?: string } and it means that query type should be Record<string, any> or Record<string, string|string[]|number|number[]|boolean|undefined> 🤔

Also undefined values probably should be excluded from resulted query string

[genaby]

Also I think that array destruction in the reduce is not very effective since each iteration will create new array each time.