Try this-

function isUrl(s) {
   var regexp = /(ftp|http|https)://(w+:{0,1}w*@)?(S+)(:[0-9]+)?(/|/([w#!:.?+=&%@!-/]))?/
   return regexp.test(s);
}

usage: if (isUrl("http://www.page.com")) alert("is correct") else alert("not correct");

function IsURL(url) {

    var strRegex = "^((https|http|ftp|rtsp|mms)?://)"
        + "?(([0-9a-z_!~* ().&=+$%-]+: )?[0-9a-z_!~* ().&=+$%-]+@)?" //ftp的user@
        + "(([0-9]{1,3}.){3}[0-9]{1,3}" // IP形式的URL- 199.194.52.184
        + "|" // 允许IP和DOMAIN（域名）
        + "([0-9a-z_!~* ()-]+.)*" // 域名- www.
        + "([0-9a-z][0-9a-z-]{0,61})?[0-9a-z]." // 二级域名
        + "[a-z]{2,6})" // first level domain- .com or .museum
        + "(:[0-9]{1,4})?" // 端口- :80
        + "((/?)|" // a slash isn t required if there is no file name
        + "(/[0-9a-z_!~* ().;?:@&=+$,%#-]+)+/?)$";
     var re=new RegExp(strRegex);
     return re.test(url);
 }

Debuggex Demo (Improved version which matches also localhost )

try something like this:

function isUrl(s) {
    var regexp = /(ftp|http|https)://(w+:{0,1}w*@)?(S+)(:[0-9]+)? (/|/([w#!:.?+=&%@!-/]))?/
    return regexp.test(s);
}

One for the future using the URL constructor and a basic try catch statement, it is supported in most modern browsers. Obviously no IE support...

const isUrl = (str) => {
  try {
    new URL(str);
    return true;
  } catch () {
    return false;  
  }
}

If the URL is valid it will get parsed by the constructor and return true.

If the string is not a valid URL the constructor will chuck a syntax error that will get caught and return false.

Try this code. This expression is more complete and takes into account IP address:

function checkUrl(s) {
     var regexp = /^(?:http(s)?://)?[w.-]+(?:.[w.-]+)+[w-._~:/?#[]@!$& ()*+,;=.]+$/
     return regexp.test(s); }

You can use a regular expression for checking the string

^s?https?://[-_.!~* ()a-zA-Z0-9;/?:@&=+$,%#]+$  

Regular Expressions and Javascript

Had the same task, but all of regex that I found online to check validity of a URL were failed in some test cases.

Here is the regex that worked everything:

/^(http://www.|https://www.|www.)?[a-z0-9]+([-.]{1}[a-z0-9]+)*.[a-z]{2,5}(:[0-9]{1,5})?(/.*)?/

However, If the URL was like: google.com It accepted it as valid (which in my specific case, was considered as invalid)

It worked the best I had found. Worked like a charm!

When given the option, I prefer the simplest solution.

Use _.startsWith(string, http ) if:

• You don t mind if URL is invalid
• You re sure the URL being checked will always start with http
• You don t expect the string to be another value that might start also with http