Converting string to int in javascript returns NaN

Question

I am trying to convert a phone number on a web page into an integer value but it repeatedly returns NaN, despite being a number. This is part of a chrome extension. My code is as follows:

currNum = String(document.getElementsByClassName("number")[0].innerHTML).trim()
console.log("First: " + currNum)

currNum = currNum.replace("(","").replace(")","").replace("-","").replace(" ","")
console.log("Second: " + currNum)

currNum = parseInt(currNum)
console.log("Third: " + currNum)

The logged output is:

‪First: ‪(206) 000-0000
Second: ‪2060000000
Third: ‪NaN

Is there something about this number that can't be cast to an int?

Thanks

There's a special non-visible character at the start of the currNum value. It's probably there in your source HTML content also; in fact that's the only place it could have come from. — Pointy
– Pointy, Commented Mar 2, 2022 at 2:38
Specifically it's character 202A, the "left-to-right embedding" character. That will cause parseInt() to fail. — Pointy
– Pointy, Commented Mar 2, 2022 at 2:38
To your .replace() chain you can add .replace(/[^ -~]/g, "") to get rid of it — Pointy
– Pointy, Commented Mar 2, 2022 at 2:46
There's a ✥Note added about the placement of the hyphen in the regex. It's just a precaution. — zer00ne
– zer00ne, Commented Mar 2, 2022 at 3:03

zer00ne · Accepted Answer · 2022-03-02 03:11:37Z

2

Use a regex (ie /[()\s-]/g)^✥ as the first param of .replace() and instead of " " for a space, use \s which will match all types of whitespace (including the 202A, Pointy mentioned). Also, replace .innerHTML with .textContent.

^{✥Note: /[()\s-]/g will match each (, ), -, and whitespace. Place the - at the end of expression or it could be misinterpreted as a range.}

let currNum = String(document.querySelector(".number").textContent).trim()
console.log("First: " + currNum)

currNum = currNum.replace(/[()\s-]/g,"");
console.log("Second: " + currNum)

currNum = parseInt(currNum)
console.log("Third: " + currNum)

<address>
  <p class='number'>(206) 555-0000</p>
</address>

edited Mar 2, 2022 at 3:11

answered Mar 2, 2022 at 2:54

zer00ne

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4 Comments

Pointy Over a year ago

Well the plain space (" ") is character 32 (decimal; 0x20) in the basic Latin page, so [^ -~] will reliably strip out any character codes that don't fall into the basic page visible (non-"control") character range.

Pointy Over a year ago

However of course the code you have will also work.

Pointy Over a year ago

oh I see you're knocking them out with one replace, carry on then.

zer00ne Over a year ago

Never occured to me to use the literal space as a class, clever.

tenshi · Accepted Answer · 2022-03-02 03:14:18Z

-1

currNum = currNum.replace(/[\s()-]/g, '')

answered Mar 2, 2022 at 3:14

tenshi

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