setup axios and php header

js_php.txt

// php

header('Access-Control-Allow-Credentials: true');
header('Access-Control-Allow-Origin: http://localhost:8080');

// js

window.app = {}
window.axios = require('axios')
window.axios.defaults.withCredentials = true
window.axios.interceptors.response.use(function (response) {
	window.app.csrf = response.data.csrf
	let nm = Object.keys(response.data.csrf)[0], key = response.data.csrf[nm];
	return response;
}, function (error) {
	return Promise.reject(error);
})
window.axios.defaults.transformRequest = function(data){
	if(window.app && window.app.hasOwnProperty('csrf')){
		let nm = Object.keys(window.app.csrf)[0], key = window.app.csrf[nm];
		data[nm] = key;
	}
	return data;
}

/*
note to self: 
- CORS always send OPTIONS request to server before actually send POST or GET to server
- process OPTIONS response from server to set/save csrf response for next ajax use (interceptors.response.use)
- append csrf data when POST to server (transformRequest)
*/