firebase.json

{
    "hosting":{
        "public": "build" ,
        "headers": [
            {
                "source": "/",
                "headers":[
                    {"key": "Link", "value": "<https://cdn-images-1.medium.com>; rel=dns-prefetch"},
                    {"key": "Link", "value": "<https://api.rss2json.com>; rel=dns-prefetch"}
                ]  
            },
            {
                "source": "**/*.@(js|css)",
                "headers":[
                    {"key": "Cache-Control","value": "max-age=108000000"}
                ]  
            },
            {
                "source": "**/*.@(eot|otf|ttf|ttc|woff|font.css)",
                "headers":[
                    {"key": "Cache-Control","value": "max-age=108000000"}
                ]  
            },
            {
                "source": "**/*.@(jpg|jpeg|gif|png)",
                "headers":[
                    {"key": "Cache-Control","value": "max-age=108000000"}
                ]  
            },
            {
                "source": "/service-worker.js", 
                "headers": [
                    {"key": "Cache-Control", "value": "no-cache"}
                ]
            }
        ],
        "rewrites": [{
            "source": "**",
            "destination": "/index.html" 
        }]
    }
}