Getting port from URL string using Javascript [duplicate]

问题

I would like a function in javascript that will get as a parameter an url and will return the port of that URL as it follows:

If there's a http or https (port 80 / 443) it won't be shown in url structure but I want them returned anyway.
If there's another port, I want that to be returned.

Example:

function myFunction(url){
    something here
    ...
    return port
}

I've seen that this can be done easy using some additional libraries but I do not want to use one. I didn't work with js since now and I would really appreciate if somebody will also be able to explain his solution.

回答1:

From what I get, you don't want to use location as the URL to subtract the port from, just any string as an URL. Well, I came up with this, for such a case. This function takes any string (but you can pass it the location URL anyway, and it works the same):

function getPort(url) {
    url = url.match(/^(([a-z]+:)?(\/\/)?[^\/]+).*$/)[1] || url;
    var parts = url.split(':'),
        port = parseInt(parts[parts.length - 1], 10);
    if(parts[0] === 'http' && (isNaN(port) || parts.length < 3)) {
        return 80;
    }
    if(parts[0] === 'https' && (isNaN(port) || parts.length < 3)) {
        return 443;
    }
    if(parts.length === 1 || isNaN(port)) return 80;
    return port;
}

It gets the base url from the string.
It splits the base url into parts, by ':'.
It tries to parse the digits-only part of the port (the last element of the parts array) into an integer.
If the URL starts with 'http' AND the port is not a number or the length of the URL parts array is less than 3 (which means no port was implied in the URL string), it returns the default HTTP port.
Same thing goes for 'https'.
If the length was 1, it means no protocol nor port was provided. In that case or in the case the port is not a number (and again, no protocol was provided), return the default HTTP port.
If it passes through all these tests, then it just returns the port it tried to parse into an integer at the beginning of the function.

回答2:

Here is a regex based solution (the regex is not bullet proof):

var urls = [
  "http://localhost/path/",
  "https://localhost/",
  "http://localhost:8080",
  "https://localhost:8443/path",
  "ftp://localhost/"
];
var i;
for (i = 0; i < urls.length; i++) {
  console.log(urls[i], getPortFromURL(urls[i]));
}

function getPortFromURL(url) {
  var regex = /^(http|https):\/\/[^:\/]+(?::(\d+))?/;
  var match = url.match(regex);
  if (match === null) {
    return null;
  } else {
    return match[2] ? match[2] : {http: "80", https: "443"}[match[1]];
  }
}

<!-- nothing here, see console -->

回答3:

hope the following code will help

function getPort(){
var port==location.port;
if(port=="")
{
if(location.protocol=="http:")
  return "80";
else
  return "443";
return port;
}

来源：https://stackoverflow.com/questions/29839793/getting-port-from-url-string-using-javascript

标签

javascript

regex