transformResponse docs misleading

I’ve recently used transformRequest to get rid of the Authorization header. It took me a while to get the correct way to pass on the data. Documentation says:

 // `transformResponse` allows changes to the response data to be made before
 // it is passed to then/catch
 transformResponse: [function (data) {
    // Do whatever you want to transform the data
    return data;
 }],

but if you use this exact code the data are passed in a wrong format (a list with an object). At last I used:

transformResponse: [function (data) {
      delete headers.common.Authorization
      return JSON.stringify(data)
      return data;
 }],

I’m definitely a beginner in this specific field but I found the documentation misleading and if what I ended up doing is correct I’d appreciate the documentation to be updated.

[mspiderv]

@sandroden The following code overrides default axios transformResponse array of functions.

transformResponse: [function (data) {
  // something here ...
}],

If you want to add your own transformResponse function, then do not override the whole array. Just preppend your function to that array using this code:

transformRequest: [(data, headers) => {
  // Do whatever you want here, for example headers.Authorization = `Bearer ${jwt}`
  return data
}, ...axios.defaults.transformRequest]

The whole magic is in ...axios.defaults.transformRequest

[stefanozanini]

@sandroden The following code overrides default axios transformResponse array of functions.

transformResponse: [function (data) {
  // something here ...
}],

If you want to add your own transformResponse function, then do not override the whole array. Just preppend your function to that array using this code:

transformRequest: [(data, headers) => {
  // Do whatever you want here, for example headers.Authorization = `Bearer ${jwt}`
  return data
}, ...axios.defaults.transformRequest]

The whole magic is in ...axios.defaults.transformRequest

How can one do this in TypeScript? I get the following error:

Type 'AxiosTransformer | AxiosTransformer[] | undefined' is not an array type or a string type. Use compiler option '--downlevelIteration' to allow iterating of iterators.ts(2569)

According to Axios types it doesn’t have to be an array.

Not the perfect solution, but i managed to bypass the error doing something like this:

transformRequest: [(data, headers) => {
  // Do whatever you want here, for example headers.Authorization = `Bearer ${jwt}`
  return data
}, ...(axios.defaults.transformRequest as AxiosTransformer[])]