Javascript：检查网址是否有效，并以“ http //”或“ https：//”开头

Question

I want to test my urls validity , which should start with http:// or https:// ,

i ve used this RegExp :

private testIfValidURL(str) {
    const pattern = new RegExp('^(https?:\\/\\/)?' + // protocol
      '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|' + // domain name
      '((\\d{1,3}\\.){3}\\d{1,3}))' + // OR ip (v4) address
      '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*' + // port and path
      '(\\?[;&a-z\\d%_.~+=-]*)?' + // query string
      '(\\#[-a-z\\d_]*)?$', 'i'); // fragment locator
    return !!pattern.test(str);
  }

This would work , execpt one case :

To consider it as valid , my urls should always start with http:// or https:// , but with my function , urls like www.abcd.com would be treated as valid urls which is not enough for me.

Sugesstions ?

Answer 1

Just change ^(https?:\\\\/\\\\/)?' to ^(https?:\\\\/\\\\/)' , the ? means that you want to match zero or one occurnece of a pattern. You actually want exactly one occurence, so don't use ? :)

From regular-expressions :

? - Makes the preceding item optional. Greedy, so the optional item is included in the match if possible.

Answer 2

You can remove the (...)? chars, so it will be mandatory to have a http or https sequence first.

 function testIfValidURL(str) { const pattern = new RegExp('^https?:\\\\/\\\\/' + // protocol '((([az\\\\d]([az\\\\d-]*[az\\\\d])*)\\\\.)+[az]{2,}|' + // domain name '((\\\\d{1,3}\\\\.){3}\\\\d{1,3}))' + // OR ip (v4) address '(\\\\:\\\\d+)?(\\\\/[-az\\\\d%_.~+]*)*' + // port and path '(\\\\?[;&a-z\\\\d%_.~+=-]*)?' + // query string '(\\\\#[-az\\\\d_]*)?$', 'i'); // fragment locator return !!pattern.test(str); } console.log(testIfValidURL('www.abcd.com')); console.log(testIfValidURL('http://www.abcd.com')); console.log(testIfValidURL('https://www.abcd.com')); console.log(testIfValidURL('htt://www.abcd.com'));