[Real] Typescript has no type

If i pass an integer to the function’s parameter “from”, it will become integer and say it doesn’t has “includes” function, since it is belong to class string. This code is tested in SharePoint online with reactjs and typescript.

Below is my tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "jsx": "react",
    "declaration": true,
    "sourceMap": true,
    "experimentalDecorators": true,
    "skipLibCheck": true,
    "outDir": "lib",
    "typeRoots": [
      "./node_modules/@types",
      "./node_modules/@microsoft"
    ],
    "types": [
      "es6-promise",
      "webpack-env"
    ],
    "lib": [
      "es5",
      "dom",
      "es2015.collection"
    ]
  },
  "include": [
    "src/**/*.ts"
  ],
  "exclude": [
    "node_modules",
    "lib"
  ]
}