Display alert if certain text

Hi guys

I want to display a error message if a certain value is choosen

            var inpObjs = document.getElementsByName('typeofbike[]');        
        validChars=/^[a-zA-Z\\d]{16}$/;
            for(i=0; i < inpObjs.length; i++){
                if(validChars.test(inpObjs[i].value='I will be using my own bike')){
                   alert("Please ring the office");
                   return false;
                }
            }

Where am I going wrong?