Fix interceptor documentation: use LIFO instead of FILO and clarify execution order

Co-authored-by: arthurfiorette <47537704+arthurfiorette@users.noreply.github.com>
This commit is contained in:
copilot-swe-agent[bot] 2025-12-08 13:26:10 +00:00
parent 0569de517b
commit 9f917b76cd
2 changed files with 7 additions and 107 deletions

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@ -5,17 +5,18 @@ inconsistencies. Which is explained in the next section.
## TL;DR
- **Request** interceptors registered before `setupCache()` are ran before and
registrations made after are ran after.
- **Response** interceptors registered before `setupCache()` are ran **after** and
registrations made after are ran **before**.
- **Request** interceptors registered **before** `setupCache()` run **before** the cache
interceptor; those registered **after** `setupCache()` run **after** the cache interceptor.
- **Response** interceptors registered **before** `setupCache()` run **after** the cache
interceptor; those registered **after** `setupCache()` run **before** the cache
interceptor.
## Explanation
Axios interceptors are ran differently for the request and response ones.
- **Request interceptors** are FILO _(First In Last Out)_
- **Response interceptors** are FIFO _(First In First Out)_
- **Request interceptors** are executed in **reverse order** - the last interceptor added runs first (LIFO - _Last In First Out_)
- **Response interceptors** are executed in **normal order** - the first interceptor added runs first (FIFO - _First In First Out_)
As explained better in the
[Axios documentation](https://github.com/axios/axios#interceptors) and in

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@ -1,101 +0,0 @@
// Test to verify the actual order of axios interceptors
import Axios from 'axios';
const testAxios = () => {
const axios = Axios.create();
const order = [];
// Mock adapter that just returns a response
axios.defaults.adapter = async (config) => {
order.push('ADAPTER');
return {
data: { success: true },
status: 200,
statusText: 'OK',
headers: {},
config
};
};
// Add interceptors BEFORE setupCache
axios.interceptors.request.use((config) => {
order.push('req-1-before');
return config;
});
axios.interceptors.request.use((config) => {
order.push('req-2-before');
return config;
});
axios.interceptors.response.use((response) => {
order.push('res-1-before');
return response;
});
axios.interceptors.response.use((response) => {
order.push('res-2-before');
return response;
});
// Simulate setupCache by adding interceptors
axios.interceptors.request.use((config) => {
order.push('req-CACHE');
return config;
});
axios.interceptors.response.use((response) => {
order.push('res-CACHE');
return response;
});
// Add interceptors AFTER setupCache
axios.interceptors.request.use((config) => {
order.push('req-3-after');
return config;
});
axios.interceptors.request.use((config) => {
order.push('req-4-after');
return config;
});
axios.interceptors.response.use((response) => {
order.push('res-3-after');
return response;
});
axios.interceptors.response.use((response) => {
order.push('res-4-after');
return response;
});
return { axios, order };
};
// Run the test
(async () => {
const { axios, order } = testAxios();
await axios.get('http://test.com');
console.log('\nActual execution order:');
console.log(order.join(' -> '));
console.log('\n\nRequest interceptors order:');
const reqOrder = order.filter(x => x.startsWith('req-'));
console.log(reqOrder.join(' -> '));
console.log('\nResponse interceptors order:');
const resOrder = order.filter(x => x.startsWith('res-'));
console.log(resOrder.join(' -> '));
console.log('\n\nConclusion:');
console.log('Request interceptors are executed in REVERSE order (Last In First Out)');
console.log(' - req-4-after runs FIRST (added last)');
console.log(' - req-1-before runs LAST (added first)');
console.log('');
console.log('Response interceptors are executed in NORMAL order (First In First Out)');
console.log(' - res-1-before runs FIRST (added first)');
console.log(' - res-4-after runs LAST (added last)');
})();