How to Add Http:// If It Doesn't Exist in the Url

How to add http:// if it doesn't exist in the URL

A modified version of @nickf code:

function addhttp($url) {
    if (!preg_match("~^(?:f|ht)tps?://~i", $url)) {
        $url = "http://" . $url;
    }
    return $url;
}

Recognizes ftp://, ftps://, http:// and https:// in a case insensitive way.

How can I add http:// to a URL if no protocol is defined in JavaScript?

Use the same function in JavaScript:

function addhttp(url) {
    if (!/^(?:f|ht)tps?\:\/\//.test(url)) {
        url = "http://" + url;
    }
    return url;
}

How to add http:// if it doesn't exist in a string containing multiple URLs

Use the g modifier. Without it, your regexp will only find the first match.
Also, String.replace() doesn't return a Promise. You don't need await.

const str = ` Unroll the pastry on to a lightly floured work surface. Cut is [Google](www.google.com/) 
    into 2 long rectangles. Cut the large rectangle in half lengthways, then cut both smaller reckk
    Bake in the oven for 25–30 minutes, or until the pastry has turned golden-brown and looks crisp. 
    Remove from the oven and leave to cool slightly before serving. Unroll the pastry on to a lightly floured work surface. 
    this is my [web](www.stackoverflow.com), this is [Google](https://www.google.com/) 
    Cut into 2 long rectangles. Cut the large rectangle in half lengthways, then cut both smaller rectangles into eight equal sections. You now have 16 rectangles in total.
    Brush one end of each rectangle with a little of the beaten egg`;
    
function urlify(text) {
   var urlRegex = new RegExp(
    '([a-zA-Z0-9]+://)?([a-zA-Z0-9_]+:[a-zA-Z0-9_]+@)?([a-zA-Z0-9.-]+\\.[A-Za-z]{2,4})(:[0-9]+)?(/.*)?', 
    'g'
   );
  return text.replace(urlRegex, (url) => {
   if (url.search(/^http[s]?\:\/\//) === -1) {
    return 'http://' + url;
   } else {
     return url;
   }
  });
}
  
console.log(urlify(str));

Prepending http:// to a URL that doesn't already contain http://

A simple solution for what you want is the following:

var prefix = 'http://';
if (s.substr(0, prefix.length) !== prefix)
{
    s = prefix + s;
}

However there are a few things you should be aware of...

The test here is case-sensitive. This means that if the string is initially Http://example.com this will change it to http://Http://example.com which is probably not what you want. You probably should also not modify any string starting with foo:// otherwise you could end up with something like http://https://example.com.

On the other hand if you receive an input such as example.com?redirect=http://othersite.com then you probably do want to prepend http:// so just searching for :// might not be good enough for a general solution.

Alternative approaches

Using a regular expression:

if (!s.match(/^[a-zA-Z]+:\/\//))
{
    s = 'http://' + s;
}

Using a URI parsing library such as JS-URI.

if (new URI(s).scheme === null)
{
    s = 'http://' + s;
}

Related questions

Javascript equalsIgnoreCase: case insensitive string comparation
javascript startswith
How do I parse a URL into hostname and path in javascript?

Add http:// prefix to URL when missing

A simple solution which may not work in all cases (i.e. 'https://'):

if (strpos($aProfileInfo['Website'],'http://') === false){
    $aProfileInfo['Website'] = 'http://'.$aProfileInfo['Website'];
}

How can I prepend http to a url if it doesn't begin with http?

Python do have builtin functions to treat that correctly, like

p = urlparse.urlparse(my_url, 'http')
netloc = p.netloc or p.path
path = p.path if p.netloc else ''
if not netloc.startswith('www.'):
    netloc = 'www.' + netloc

p = urlparse.ParseResult('http', netloc, path, *p[3:])
print(p.geturl())

If you want to remove (or add) the www part, you have to edit the .netloc field of the resulting object before calling .geturl().

Because ParseResult is a namedtuple, you cannot edit it in-place, but have to create a new object.

PS:

For Python3, it should be urllib.parse.urlparse

Add http(s) to URL if it's not there?

Use a before filter to add it if it is not there:

before_validation :smart_add_url_protocol

protected

def smart_add_url_protocol
  unless url[/\Ahttp:\/\//] || url[/\Ahttps:\/\//]
    self.url = "http://#{url}"
  end
end

Leave the validation you have in, that way if they make a typo they can correct the protocol.

Add http://www. in the text if not Exist

You can do like this

String url = textView.getText().toString();
if(!url.startsWith("www.")&& !url.startsWith("http://")){
  url = "www."+url;
}
if(!url.startsWith("http://")){
  url = "http://"+url;
}

You can use this url to display content in WebView

Hope this will solve your problem

Add http:// to NSURL if it's not there

NSString *urlString = @"google.com";
NSURL *webpageUrl;

if ([urlString hasPrefix:@"http://"] || [urlString hasPrefix:@"https://"]) {
    webpageUrl = [NSURL URLWithString:urlString];
} else {
    webpageUrl = [NSURL URLWithString:[NSString stringWithFormat:@"http://%@", urlString]];
}

NSURLRequest *urlRequest = [NSURLRequest requestWithURL:webpageUrl];
[self.myWebView loadRequest:urlRequest];

How to Add Http:// If It Doesn't Exist in the Url