Getting NaN in Javascript With Simple Calculation [duplicate]

Question

<script>
function runCals() {
   var milesRun = document.getElementById("runDist")
   var runCals = Number(milesRun) * 96
   document.getElementById("cals").innerHTML = runCals
}

</script>

I am getting NaN and I do not understand why. I visited many stack questions but none I found had my specific problem.

Why am I getting NaN and how do I fix it?

What do you get if you do console.log(Number(milesRun))?

developer_hatch
– developer_hatch

2017-06-06 01:14:21 +00:00
Commented Jun 6, 2017 at 1:14 — developer_hatch
– developer_hatch, Commented Jun 6, 2017 at 1:14
My computer has inspect element blocked.

John Mann
– John Mann

2017-06-06 01:15:07 +00:00
Commented Jun 6, 2017 at 1:15 — John Mann
– John Mann, Commented Jun 6, 2017 at 1:15

Joe Thomas · Accepted Answer · 2019-02-24 22:13:54Z

3

milesRun is not a number, it's a DOM node, so you can't convert it to a number. If it's an input box just add .value to the end of the selector to extract the value inputted into it. e.g.

function runCals() {
   var milesRun = document.getElementById("runDist").value
   var runCals = Number(milesRun) * 96
   document.getElementById("cals").innerHTML = runCals
}

edited Feb 24, 2019 at 22:13

answered Jun 6, 2017 at 1:15

Joe Thomas

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7 Comments

John Mann Over a year ago

Thanks so much! I will accept this answer once this site enables me to, in 12 minutes.

Sebastian Simon Over a year ago

There’s some wrong terminology here. milesRun is a value. It’s just an object, instead of the intended number.

Joe Thomas Over a year ago

Lol no worries, we all make silly mistakes sometimes.

Joe Thomas Over a year ago

@Xufox From Google Dictionary "Value" the numerical amount denoted by an algebraic term; a magnitude, quantity, or number. But you're right in that it might be a bit confusing so I added "number" value. It wasn't wrong terminology.

Sebastian Simon Over a year ago

@joe-tom In JavaScript terms, all of those things are values. There’s a distinction of primitive values, but objects are values, too.

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