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)">

Answer 1

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);
    }
...