How can I cast a string to number in an response using axios?

Question

I am using Axios to execute a GET request to a public API. This API return a numeric value as string. I need to cast this value a numeric value. My application runs using tsc, so I expect the result of my object to be a numeric value, but it's not.

Axios Response

[
  {
    "name": "foo1",
    "value": "8123.3000"
  },
  {
    "name": "foo2",
    "value": "5132.2003"
  },
  {
    "name": "foo3",
    "value": "622.0000"
  }
]

Expected Output

[
  {
    "name": "foo1",
    "value": 8123.3
  },
  {
    "name": "foo2",
    "value": 5132.2003
  },
  {
    "name": "foo3",
    "value": 622
  }
]

My code is very simple,

interface MyObj {
  myString: string;
  myNumber: number;
}

(async () => {
  let { data }: AxiosResponse<MyObj> = await axios.get<MyObj>("/public/data");
  console.log(data);
})();

I try to use interface, class, the interface Number. Nothing worked.

I leave an example of code to try it.

How can I get the expected output without manually converting each value one by one?

Answer 1

Axios does not change the type of properties in the response. Please verify that the server does not send you the wrong types.

---

Edit

From your comment, it seems that the server sends you the vslue as string instead of as number. In this case I would suggest working with Ajv (https://github.com/ajv-validator/ajv) so you can create a schema that describes how the response looks like. Ajv cn also transform the value from string to number for you:

const Ajv = require('ajv')

const ajv = new Ajv({
  // allow chaning the type of some values from type X to type Y. depends on the source and target type:
  // https://ajv.js.org/guide/modifying-data.html#coercing-data-types
  // X => Y rules: https://ajv.js.org/coercion.html
  coerceTypes: true,
})

const schema = {
  type: 'array',
  items: {
    type: 'object',
    properties: {
      name: { type: 'string' },
      value: { type: 'number' },
    },
    required: ['name', 'value'],
    additionalProperties: false,
  },
}

const data = { name: 1, value: '1.1' }

console.log(typeof data.value === 'number') // false!

const valid = ajv.validate(schema, data)
if (!valid) {
  console.log(ajv.errors)
  process.exit(1)
}

console.log(typeof data.value === 'number') // true!