Matching exactly two consecutive spaces in Google Apps Scripts - regex

Question

I'm trying to match exactly two consecutive spaces using DocumentApp.getActiveDocument().getBody().replaceText() and replace them with a single space.
Unfortunately, it only supports some of regex (https://github.com/google/re2/wiki/Syntax).
I've tried DocumentApp.getActiveDocument().getBody().replaceText("[^ ] {2}[^ ]", " ") but that matches the characters sourrounding the text aswell.
I've tried DocumentApp.getActiveDocument().getBody().replaceText("([^ ]) {2}([^ ])", "$1 $2") but this outputs "$1 $2" rather then "character character"
I've tried DocumentApp.getActiveDocument().getBody().replaceText(" {2}", " ") but that also matches two spaces within a greater group of spaces.

Answer 1

It was difficult (for me) to write a single regular expression for required replacements, because surrounding characters (non-spaces) were also replaced each time. Moreover, in general case we should take into account special cases when spaces position is at the very beginning of the string or at the end.
As a result I suggest 2 functions for all kinds of replacements below:
function replaceDoubleSpace() {
var body = DocumentApp.getActiveDocument().getBody();
var count = replaceWithPattern('^ $', body);
Logger.log(count + ' replacement(s) done for the entire string');
count = replaceWithPattern('[^ ]{1} [^ ]{1}', body);
Logger.log(count + ' replacement(s) done inside the string');
count = replaceWithPattern('^ [^ ]{1}', body);
Logger.log(count + ' replacement(s) done at the beginning of the string');
count = replaceWithPattern('[^ ]{1} $', body);
Logger.log(count + ' replacement(s) done at the end of the string');
}
function replaceWithPattern(pat, body) {
var patterns = [];
var count = 0;
while (true) {
var range = body.findText(pat);
if (range == null) break;
var text = range.getElement().asText().getText();
var pos = range.getStartOffset() + 1;
text = text.substring(0, pos) + text.substring(pos + 1);
range.getElement().asText().setText(text);
count++;
}
return count;
}
Of course, the first function may be simplified, but it becomes less readable in this case:
function replaceDoubleSpace() {
var body = DocumentApp.getActiveDocument().getBody();
var count = replaceWithPattern('^ $|[^ ]{1} [^ ]{1}|^ [^ ]{1}|[^ ]{1} $', body);
Logger.log(count + ' replacement(s) done');
}