VScode - replace captured group with the values - html

Question

i have a bunch of strings in code such as:
<td style="background-color:#fdfdff"> </td>
and
<td> </td>
in one file.
The goal is to replace from first example with 0, while from second example with - (dash)
I'm using VScode regex, but I can't find the way to replace captured groups with specific values, as $1, $2 groups refer to original string groups.
This one is just example, how I'm trying to achieve this, but VScode don't ignore grouped regex.

Answer 1

An alternative process is to use a snippet which can do conditional replacements. With this snippet:
"replaceTDs": {
"prefix": "tdr", // whatever prefix you want
"body": [
"${TM_SELECTED_TEXT/(?<=\">)( )|( )/${1:+0}${2:+-}/g}",
]
}
The conditional replacements can be quite simple since you first find and select only the two alternative texts you are interested in. So
find: <td\s*(style="[^"]*"\s*)> </td>|<td> </td> old version
This simpler find will probably work for you:
<td\s*(style="[^"]*")?\s*> </td>
Don't replace, rather Control+Shift+L : selects all your two alternatives. Esc to focus on editor from the find widget.
Then apply your snippet, in this case type tdr+Tab
and all the changes are made. You just have to make the snippet one time and then do a single find.
This technique scales a little better than running as many find/replaces as you have replacements to do. Even with more conditional replacements it would probably be a simple change to the one snippet to add more replacements.
Also you can simplify this even more if you use a keybinding to trigger your snippet (you don't have to change focus from the find widget - or create the separate snippet). So with no snippet, but this keybinding:
{
"key": "alt+w",
"command": "editor.action.insertSnippet",
"args": {
"snippet": "${TM_SELECTED_TEXT/(?<=\">)( )|( )/${1:+0}${2:+-}/g}"
},
"when": "editorHasSelection"
}
now the same demo:

Answer 2

You can use
Search for (?<=<td\s+style="[^"]*">) (?=</td>) and replace with 0, and
Search for <td> </td> and replace with <td>-</td>, no need for a regex here.
Note that capturing groups are meant to keep captured substrings.
The first pattern matches
(?<=<td\s+style="[^"]*">) - a place in string that is immediately preceded with <td, one or more whitespaces, style=", any zero or more chars other than " and then a >
- a literal string
(?=</td>) - immediately to the right, there must be </td>.