Use javascript onblur event to default input box to 0.00 if no value is entered or if a value is less than 0

Question

Here is my onblur event with the javascript so far. There are values auto loaded into the box on the page load but if a user deletes the value or enters a value less than zero it should default to 0.00. Right now it is defaulted to NaN.

function checkformat(entry) {    
    test = entry.value;
    if (!isNaN(test)) {
        entry.value=parseFloat(entry.value).toFixed(2);
    }
    else if (isNaN(test) == true) {      
        test.value='0.00';        
    }
    else if (test < 0.00) {
        test.value = '0.00';
    }
    else {
      test.value = '0.00';
    }
    
  }

<input id='Line Item <% line %>' type="text" onkeyup="updateTotal()" placeholder="Amount" name="AmountPaying" class="field m w-input" value="<% r.AmountOwed %>" onblur="checkformat(this)">

well if the number is valid it will go into the first if, it is not going to go into the other checks. — epascarello, Oct 17 '16 at 21:12
Yes but if the user enters nothing and clicks out of the box, if goes to NaN — jreed21, Oct 17 '16 at 21:14
but -123213 is valid number so it will never go into the negative check. — epascarello, Oct 17 '16 at 21:15
Ah ok I see what you're saying about that one. But still wondering why entering nothing doesnt go to the isNaN check — jreed21, Oct 17 '16 at 21:17
`console.log(isNaN(""))` http://stackoverflow.com/questions/825402/why-does-isnan-equal-false — epascarello, Oct 17 '16 at 21:18

score 0 · Answer 1 · answered Oct 17 '16 at 21:17

Use the following funtion for IsNaN control.

function isNumeric(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
}

New Code

function checkformat(entry) {    
    test = entry.value;
    if (isNumeric(test)) {
        entry.value=parseFloat(test).toFixed(2);
    }
...

Use javascript onblur event to default input box to 0.00 if no value is entered or if a value is less than 0

1 Answers1