JavaScript verifies that user input URL address is empty and the format is correct

The code is as follows:

<script type= "Text/javascript" >


function Checkurl () {


var url = document.getElementById (' URL '). value;


if (url== ') {


alert (' URL address cannot be empty ');


return false;


} else if (!isurl (URL)) {


alert (' URL should be in the format of Http://www.jb51.net ');


return false;


} else {


return true;


}


return false;


}

function Isurl (str)
{
varreg=/[0-9a-za-z]+. (html|htm|shtml|jsp|asp|php|com|cn|net|com.cn|org) $/;
Must contain. (The last one is at least one character ahead) and. There is at least one word character at the back, the final character must be a word character or/
varreg=/w+. (w+|w+/) $/;
Varisurl=reg.test (str);//test (str) method is a JS correct expression built-in object can be directly called
Returnisurl;
}
</script>

The

code is as follows:


&lt;form action= "method=" post "onsubmit=" Checkurl (); " &gt;

Url:
<input type= "text" name= "url" id= "url" value= "http://www.jb51.net" onfocus= "this.value=" "/>
<br/><br/>
<input type= "Submit" value= "Fetch address" name= "get"/>
<input type= "Submit" value= "Download" name= "Download"/>
</form>

PHP detects URL address validity

The code is as follows

The

code is as follows:


;?


function Is_url ($str) {


return Preg_match ("/^http://[a-za-z0-9]+.[ a-za-z0-9]+[/=?%-&amp;_~ ' @[] ': +!] * ([^&lt;&gt; "]) *$/", $str);


}


?&gt;

If you want to try the normal method we can use the file_get_contents () function to verify it.