For example:

"1+1=2".replace(/=/,"aa");
"1+1=2".replace(/\=/,"aa");

return the same result.

Does it mean I don't have to escape "=" (the equal sign) in JavaScript? I remembered that I always have to escape equal sign in Java and .NET.

I tried to find some info from .0/index.html but didn't e up with anything.

Can anyone help me find if the specification talks about escaping the equal sign?

For example:

"1+1=2".replace(/=/,"aa");
"1+1=2".replace(/\=/,"aa");

return the same result.

Does it mean I don't have to escape "=" (the equal sign) in JavaScript? I remembered that I always have to escape equal sign in Java and .NET.

I tried to find some info from https://www.ecma-international/ecma-262/7.0/index.html but didn't e up with anything.

Can anyone help me find if the specification talks about escaping the equal sign?

• javascript
• regex

• 12 = has no special meaning in regular expressions, it doesn't need to be escaped. – Barmar Commented Nov 24, 2016 at 0:32
• 3 They don't escape it in Java in this question – Barmar Commented Nov 24, 2016 at 0:35
• 3 And here's a question that doesn't escape it: stackoverflow./questions/31490169/lookbehind-with-equal-sign – Barmar Commented Nov 24, 2016 at 0:36
• @Barmar how would you explain the usage of = in Positive lookahead (?= )? I thought = is then a special character that always needs to be escaped.. – user746461 Commented Nov 24, 2016 at 0:50
• 3 Lots of characters have special meaning after (?, but they don't have special meaning elsewhere, so they don't need to be escaped. – Barmar Commented Nov 24, 2016 at 0:54

1 Answer 1

I'd go with this table in MDN web docs. You'll see that = has no special meaning - just as @Barmar stated. You referred to lookaheads, which use ?=, but without the leading ? it's just an equal sign.

There are not many special characters which needs an additional special character to "work", I guess that's why it's confusing. Think of it as - in bination with [ and ]:

• 0-9 matches "0-9"
• [0-9] matches "0" and "1" and ... and "9"
• [0\-9] matches "0" and "1" and ... and "9" and "-"

So just - has no meaning and does not have to be escaped, only if bined with square brackets. The same applies to = with/without ?.