Attributes with values like "20vw" get converted incorrectly

[PaulBGD]

Sample repo: https://github.com/PaulBGD/svelte-pass-number

Basically comes down to this line of code:

svelte/src/generators/dom/visitors/attributes/addComponentAttributes.js

Line 31 in 7cd8683

const result = isNaN( parseFloat( value.data ) ) ? JSON.stringify( value.data ) : value.data;

Attributes that start with a number like <Comp value="10px" gets parsed into the number 10 by parseFloat so it outputs it as

initialData = {
  value: 10vw // throws parse error here
}

I suggest replacing the isNaN check with

String(parseFloat(value.data)) !== value.data

or something that better checks if it's a number or not.

[Ryuno-Ki]

Hope, that you never encounter an input with leading zero … that is, better pass 10 as second parameter to parseFloat to denote the base (leading zero leads to interpretation as octal number).

[mrkishi]

@Ryuno-Ki That's not a thing for parseFloat: there's no radix argument. For parseInt, I believe it's not a problem for IE9+ support.

[Ryuno-Ki]

Looking it up on MDN and you're right.

[Rich-Harris]

Either way, we're using isNaN now