function isValidURL(string) {

  var res = string.match(/(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)/g);

  return (res !== null)

};

​

var testCase1 = "http://en.wikipedia.org/wiki/Procter_&_Gamble";

​

alert(isValidURL(testCase1)); 

​

function isValidHttpUrl(string) {

  let url;

  try {

    url = new URL(string);

  } catch (_) {

    return false;  

  }

​

  return url.protocol === "http:" || url.protocol === "https:";

}

const isAbsoluteUrl = url => /^[a-z][a-z0-9+.-]*:/.test(url);

​

// Example

isAbsoluteUrl('https://1loc.dev');          // true

isAbsoluteUrl('https://1loc.dev/foo/bar');  // true

isAbsoluteUrl('1loc.dev');                  // false

isAbsoluteUrl('//1loc.dev'); 

  const isUrl = string => {

      try { return Boolean(new URL(string)); }

      catch(e){ return false; }

  }

​

let urlString = "https://www.example.com/";

​

if (urlString.startsWith("https://") || urlString.startsWith("http://")) {

     console.log("valid");

} else {

     console.log("unvalid");

}