# My regular expression is not working

**URL:** <https://discourse.processing.org/t/my-regular-expression-is-not-working/47004>\
**Category:** Coding Questions\
**Created:** [August 21, 2025, 7:28pm UTC](https://discourse.processing.org/t/my-regular-expression-is-not-working/47004 "2025-08-21T19:28:39Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![quark](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/quark/32/26_2.png) [@quark](https://discourse.processing.org/u/quark)\
**Post date:** [August 21, 2025, 7:28pm UTC](https://discourse.processing.org/t/my-regular-expression-is-not-working/47004/1 "2025-08-21T19:28:39Z")

</div>

I am trying to parse this string to find attribute assignments  
`<body width="500" linegap="2" paragap="8" align="justify" font="courier new">' `

An attribute assignment is of the format  
`name="value"`

where the format is

- 1 or more word characters
- 0 or more spaces
- = symbol
- 0 or more spaces
- 1 " or ’ character
- 0 or 1 minus sign
- 1 or more word characters
- 0 or 1 space
- 1 or more word characters
- 1 " or ’ character

So here is the sketch  
The regular expression is

```auto
/\w+\s*=\s*[\'\"]-?\w+\s?\w+[\'\"]/g

```

My sketch is shown below but when I run it I get this output

```
============ Nbr Tokens 3 ==============

-----------------------------------------------------
Pos: 000 Length: 011 Token: |width="500"|  
Pos: 001 Length: 015 Token: |align="justify"|  
Pos: 002 Length: 018 Token: |font="courier new"|
```

Notice that 2 of the attribute assignments are not found. I admit I am no expert in using regular expression so I assume I am missing something obvious

Any help would be appreciated.

Sketch code

```auto
function setup() {
    createCanvas(640, 400);
    let s = '<body width="500" linegap="2" paragap="8" align="justify" font="courier new">';
    let rgx1 = /\w+\s*=\s*[\'\"]-?\w+\s?\w+[\'\"]/g;
    let r = s.match(rgx1);

    let n = 0, out = ['\n'];
    out.push(`============ Nbr Tokens ${r ? r.length : 0} ==============`);
    out.push(s);
    out.push('-----------------------------------------------------')
    r?.forEach(e => out.push(`Pos: ${nfs(n++, 3, 0)} Length: ${nfs(e.length, 3, 0)} Token: |${e}| `));
    console.log(out.join('\n'));
}

```

---

<div class="post-metadata">

**Author:** ![davepagurek](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/davepagurek/32/17535_2.png) [@davepagurek](https://discourse.processing.org/u/davepagurek)\
**Post date:** [August 21, 2025, 7:51pm UTC](https://discourse.processing.org/t/my-regular-expression-is-not-working/47004/2 "2025-08-21T19:51:42Z")

</div>

Here’s an attempt at a fix: [Waiting medusaceratops by davepagurek -p5.js Web Editor](https://editor.p5js.org/davepagurek/sketches/r9P6CQRGm)

My regex looks like this: `/\w+\s*=\s*['"][^'"]*['"]/g`

The main difference is that between the quotes, rather than trying to match possibly multiple words with possible spaces in it, which would fail to match anything with less than 2 characters, I’m just matching “any number of non-quote characters” (`[^'"]*`) in between (including 0 characters in length, for an empty attribute.)

Edit: also in case it helps with understanding, your regex would match all attributes in your example if you change the last two `\w+`s into `\w*`. Having two `\w+`s means a minimum of two word characters required within the quotes, which is why the single-digit attributes aren’t getting caught. But probably the more general approach above would help for things like three-word attributes, or ones with other characters, like `<div style="height: 200px">`.

---

<div class="post-metadata">

**Author:** ![quark](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/quark/32/26_2.png) [@quark](https://discourse.processing.org/u/quark)\
**Post date:** [August 21, 2025, 10:07pm UTC](https://discourse.processing.org/t/my-regular-expression-is-not-working/47004/3 "2025-08-21T22:07:13Z")

</div>

> [@davepagurek](#):
>
> Having two `\w+`s means a minimum of two word characters required within the quotes

This is part of a bigger project and like most of the stuff I create it evolves.

When I started the project I anticipated the the “value” being either

1. a positive integer, or
2. a word comprising letters and numbers but no spaces

so the regex was very simple, later I realised I might need negative integers so incorporated the` -?` into the regex.

Later still I realised some string values might have a space e.g. `courier new` so hacked at the regex not realising it now required a minimum of 2 characters for any match.

So thank you for replying, the blinkers just fell away after ready your post. 😀

You’re regex is very neat and a good starting point. Since I don’t want zero-length values I have changed the regex to ` /\w+\s*=\s*['"]-?\w+[\w]*['"]/g` as it provides a closer match to the value format I want. I just need to test it fully and incorporate it into my project.

Thanks again for a very swift response. 👍