在javascript中使用input.value.match进行验证

Question

I believe I have a fairly simple problem, but I am unfortunately unable to resolve it. I have searched for a while and tried several different variations of this code but cannot seem to get it to work.

All I am trying to do is check and see if my input value has a alpha character in it opposed to a number.

Here is my js function:

function checkLetters(input) {
    var numOnly = /^[0-9]+$/;
    var hasLetters = false;
    if (!input.value.match(numOnly)) {
        hasLetters = true;
    } 
    return hasLetters;
}

and here is the code calling it:

<input type="text" name="cc_number" size="13" maxlength="11" onblur="
    if(checkLength(cc_number.value) == true) {
    alert('Sorry, that is not a valid number - Credit Card numbers must be nine digits!');
    } else if (checkLetters(cc_number.value) == true) {
    alert('Credit Card number must be numbers only, please re-enter the CC number using numbers only.');
    }">

Any help or suggestions would be appreciated.

Answer 1

You're passing cc_number.value as input , but then referencing input.value.match() , which works out to:

cc_number.value.value.match();

Just pass cc_number :

if (checkLetters(cc_number)) {
  ...
}

Answer 2

It looks like you're trying to validate credit card input. May I suggest a different approach?

function checkCardInput(input,errorId) {
  var errorNoticeArea = document.getElementById(errorId);   
  errorNoticeArea.innerHTML = ''; 
  if(!input.value) {
    errorNoticeArea.innerHTML = 'This field cannot be left blank.';   
    return;
  }
  if(!input.value.match(/[0-9]/)) {
    errorNoticeArea.innerHTML = 'You may only enter numbers in this field.';
    input.value = '';
    return; 
  }
  if(input.value.length != 9) {
    errorNoticeArea.innerHTML = 'Credit card numbers must be exactly 9 digits long.';   
    return;
  }
}

See this jsFiddle for an example use.