Using a textbox to take in an integer value for use in Javascript function. Is there a simpler way?

Question

I'm currently making a simple calculator for use in an intro to Javascript lesson. I would like to know if there's a simpler way of taking the value from a HTML input textbox as an integer than having to use the Javascript parse() method?

HTML:

<input type = "Text" id="num1">

JS:

var num1 = parseInt(document.getElementById("num1").value);

`+document.getElementById("num1").value` – elclanrs Jun 22 '14 at 20:36 — elclanrs, Jun 22 '14 at 20:36

score 1 · Accepted Answer · answered Jun 22 '14 at 20:38

1

You can force a string to be a 32-bit integer like this:

var num1 = ~~document.getElementById("num1").value;

You can, alternatively, accept a number with a possible fractional part with

var num1 = +document.getElementById("num1").value;

In both cases, you can check to see if the original string really did look like a number by using isNaN():

if (isNaN(num1)) {
  // bad input
}

answered Jun 22 '14 at 20:38

Pointy

405,095
59
585
614

ha ha I answered the linked duplicate too. I have a one-track brain. – Pointy Jun 22 '14 at 20:39

Using a textbox to take in an integer value for use in Javascript function. Is there a simpler way?

1 Answers1