Regular Expressions 101

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/
([^\s]=[^=])(?![^\s])
/
g
1st Capturing Group
([^\s]=[^=])
Match a single character not present in the list below
[^\s]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\s matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
= matches the character = literally (case sensitive)
Match a single character not present in the list below
[^=]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
= matches the character = literally (case sensitive)
Negative Lookahead
(?![^\s])
Assert that the Regex below does not match
Match a single character not present in the list below
[^\s]
\s matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
g

Test String