Intercept the front end of the Chinese string and the PHP notation

JS front-end notation:

The third parameter determines whether an ellipsis is required

function subString (str, len, Hasdot) 
{ 
    var newlength = 0; 
    var newstr = ""; 
    var chineseregex =/[^\x00-\xff]/g; 
    var Singlechar = ""; 
    var strlength = str.replace (Chineseregex, "* *"). Length; 
    for (var i = 0;i < strlength;i++) 
    { 
        Singlechar = Str.charat (i). toString (); 
        if (Singlechar.match (Chineseregex)!= null) 
        { 
            newlength = 2; 
        }     
        else 
        { 
            newlength++; 
        } 
        if (Newlength > Len) 
        {break 
            ; 
        } 
        Newstr + + Singlechar; 
    } 
     
    if (Hasdot && strlength > Len) 
    { 
        newstr + = "..."; 
    } 
    return newstr; 

Server-side PHP notation:

function Msubstr ($str, $start, $len) {
    $tmpstr = "";
    $strlen = $start + $len;
    for ($i = 0; $i < $strlen; $i + +) {
        if (Ord substr ($str, $i, 1)) > 0xa0) {
            $tmpstr. = substr ($str, $i, 2);
            $i + +;
        } else
            $tmpstr. = substr ($str, $i, 1);
    }
    return $tmpstr;
}