nodjs request is hanging on url chagne

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Javascript

Node.js

i have this code

var fs= require("fs");
var http= require("http");

var server= http.createServer(function (request, response){

    if(request.url=="/")
    {
        fs.readFile("about.html",function(error, data){
            if(error){
                response.writeHead(202,{"content-type":"text\html"});
                response.end("sorry page not found");
            }
            else{
                response.writeHead(202,{"content-type":"text/html"});
                response.write(data)
                response.end();
            }

        });
    }
    else if(request.url=="about.html")
    {
        respsonse.end("about page requies rescevd");
        
    }

});
server.listen(4000,"127.0.0.1",function(error,data){
        if(!error)
        console.log("congragts");

    } )

On Browswer:
This working fine http://localhost:4000
but when doing request for this http://localhost:4000/about.html
(when typing and enter url it become hang (loading))

and finally show no data received. why ?