How can I extract each integer or float (positive or negative) from a string in js

Question

This is my code. It still returns null and I do not know why!

var tName = "18.56x^2   -   5.45x  -3.78";
abc = tName.replace(/x/g, "").replace("^2", "").replace(/\s/g, "");
console.log(abc);

$re = "/-?\\d+(?:\\.\\d+)?/m";
$str = abc.toString();
console.log($str.match($re));

just a hint you can use `https://regex101.com/` to debug your RegExp — Aalexander, Dec 14 '20 at 08:25
https://stackoverflow.com/questions/10003683/extract-a-number-from-a-string-javascript This could help — Abdallah Elsayed, Dec 14 '20 at 08:25

Keldan Chapman · Answer 1 · 2020-12-14T08:40:33.090

3

Your regex is fine, you just set it up as a string instead of a regex literal.

When you are building RegExp constants, you want to either use the RegExp() constructor (for building from strings) or simply a regex literal. You are currently building a normal string that looks like a regex, but isn't.

Try edit this line to the following:

$re = /-?\d+(?:\.\d+)?/m;

Edit:

To access the string itself, you just need to use index 0.

var mat = $str.match($re);
console.log(mat[0])

edited Dec 14 '20 at 08:40

answered Dec 14 '20 at 08:28

Keldan Chapman

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5
21

thanks it worked, however I did not get what I wanted I think my regex is incorrect... – 7Wdev Dec 14 '20 at 08:36
i got : [ '18.56', index: 0, input: '18.56-5.45-3.78', groups: undefined ] – 7Wdev Dec 14 '20 at 08:36
Yes that is a 'match object' try add a `[0]` at the end to reference the matching string. – Keldan Chapman Dec 14 '20 at 08:37

score 1 · Answer 2 · answered Dec 14 '20 at 08:30

use regexp (not String) as param of String.prototype.match() like this:

var tName = "18.56x^2   -   5.45x  -3.78";
abc = tName.replace(/x/g, "").replace("^2", "").replace(/\s/g, "");

$re = /-?\d+(?:\.\d+)?/m;
$str = abc.toString();
console.log($str.match($re));

mplungjan · Accepted Answer · 2020-12-14T08:39:45.587

1

You need to

not quote the regex AND
not escape the \d AND
add the global flag

Have a try with this

const $re = /-?\d+(?:\.\d+)?/mg,
      tName = "18.56x^2   -   5.45x  -3.78",
      abc = tName.replace(/x/g, "").replace("^2", "").replace(/\s/g, ""),
      nums = [...abc.matchAll($re)].map(m => m[0]);
console.log(abc)
console.log(nums)

edited Dec 14 '20 at 08:39

answered Dec 14 '20 at 08:33

mplungjan

169,008
28
173
236

How can I extract each integer or float (positive or negative) from a string in js

3 Answers3