JavaScript verifies that the user entered the correct URL address

<script type= "Text/javascript" >
function Checkurl () {
var url = document.getElementById (' URL '). value;
if (url== ') {
Alert (' URL address cannot be null ');
return false;
} else if (!isurl (URL)) {
Alert (' URL format should be http://www.111cn.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 be included. (The last one. There is at least one character in front) and. There is at least one word character behind it, and the final character must be a word character or/
varreg=/w+. (w+|w+/) $/;
Varisurl=reg.test (str);//test (str) method is JS the correct expression built-in object can be called directly (www.111cn.net)
Returnisurl;
}
</script>

<form action= "" method= "Post" onsubmit= "Checkurl ();" >
Url:
<input type= "text" name= "url" id= "url" value= "http://www.111cn.net" onfocus= "this.value=" "/>
<br/><br/>
<input type= "Submit" value= "Get Address" name= "get"/>
<input type= "Submit" value= "Download" name= "Download"/>
</form>

PHP detects URL address validity

Code to copy code as follows
<?
function Is_url ($STR) {
Return Preg_match ("/^http://[a-za-z0-9]+.[ a-za-z0-9]+[/=?%-&_~ ' @[] ': +!] * ([^<> "]) *$/", $str);
}
?>

We can use the file_get_contents () function to verify if we want to try a normal method.
From:http://www.111cn.net/wy/js-ajax/50084.htm

JavaScript verifies that the user entered the correct URL address