function limit_characters(string,length,extesion){
    var newString = "";
    var i = 0;
    while(i < length && i < string.length){
        newString = newString + string.charAt(i);
        i = i + 1;
    }
    if(i < string.length){
        newString = newString + extesion;
    }
    return newString;
}