Format Numbers in JavaScript

Question

I have a web page that allows a user to enter values into fields. When a user updates a field, I want to automatically update the total displayed to the user. Because the input fields are dynamically generated, I created a JavaScript function called "update". A sample of my code is shown here:

<input type="text" id="myField1" onchange="return update(this);" />
<input type="text" id="myField2" onchange="return update(this);" />
<span id="totalCount"></span>

var total = 0;
function update(e) {
  var v = $(e).val();
  if (parseInt(v) != NaN) {
    total = total + v;
    $("#totalCount").html(total);       
  }
  return false;
}

When a user enters "2" into "myField1", "02" is displayed in the "totalCount" element. In reality, I would like to just display "2". How do I do this in JavaScript while taking into a account odd entries?

Thanks!

When you input zero, does it display 00 or 0?

Marko
– Marko

2010-11-20 17:10:09 +00:00
Commented Nov 20, 2010 at 17:10 — Marko
– Marko, Commented Nov 20, 2010 at 17:10

Gumbo · Accepted Answer · 2010-11-20 17:08:42Z

4

Since $(e).val() is a string, total + v is a string too. Use parseInt not just for the test but also when using the value:

var v = parseInt($(e).val(), 10);
if (!isNaN(v)) {
    total = total + v;
    $("#totalCount").html(total);
}

answered Nov 20, 2010 at 17:08

Gumbo

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6 Comments

Ivo Wetzel Over a year ago

Also NaN != NaN returns true use isNaN(v);

Marko Over a year ago

@Gumbo, what happens if he inputs a decimal, 2.15 for example?

Gumbo Over a year ago

@Marko: parseInt parses the input to integer. In case of 2.15 the output will be 2.

Marko Over a year ago

Yeah I thought so too, was just thinking it might be something to consider if decimal input is allowed :) +1 either way

Lars Blåsjö Over a year ago

Regarding decimals, you can use Number($(e).val()) instead of parseInt($(e).val(), 10)

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