Question

Is there any javascript function, to parse the first line of the http header?

GET /page/?id=173&sessid=mk9sa774 HTTP/1.1

The url is encoded.

I would like to get an object, like this:

{
"method" : "GET",
"url" : "/page/",
"parameters": {
  "id" : 173,
  "sessid" : "mk9sa774"
  }
}

I searched a lot, but I haven’t found anything useful.

thanks in advance,

Answer 1

First you can split on spaces:

var lineParts = line.split(' ');

Now you can get the method, unparsed path, and version:

var method  = lineParts[0];
var path    = lineParts[1];
var version = lineParts[2];

Then you can split up the path into the query string and non-query string parts:

var queryStringIndex = path.indexOf('?');
var url, queryString;
if(queryStringIndex == -1) {
    url = path, queryString = '';
}else{
    url = path.substring(0, queryStringIndex);
    // I believe that technically the query string includes the '?',
    // but that's not important for us.
    queryString = path.substring(queryStringIndex + 1);
}

If there is a query string, we can then split it up into key=value strings:

var queryStringParts = [];
if(queryStringIndex != -1) {
    queryStringParts = queryString.split('&');
}

Then we can unescape them and stuff them into an object:

var parameters = {};
queryStringParts.forEach(function(part) {
    var equalsIndex = part.indexOf('=');
    var key, value;
    if(equalsIndex == -1) {
        key = part, value = "";
    }else{
        key   = part.substring(0, equalsIndex);
        value = part.substring(equalsIndex + 1);
    }
    key   = decodeURIComponent(key);
    value = decodeURIComponent(value);
    parameters[key] = value;
});

If you really wanted to, you could then put all that data into an object:

return {
    method:     method,
    url:        url,
    version:    version,
    parameters: parameters
};

If you’re in a browser environment, that’s the only way to do it. If you’re using Node.JS, it can deal with the URL parsing for you.