javascript - How can I check if two regular expressions are the same?

If JavaScript, /\.scss$/ is a regex. I want to check whether a regex is exactly the same as another regex, however:

/\.scss$/ === /\.scss$/ // false

How can I do this? Note that I do not care about what the regex matches, I only care about the way the regex is defined.

If JavaScript, /\.scss$/ is a regex. I want to check whether a regex is exactly the same as another regex, however:

/\.scss$/ === /\.scss$/ // false

How can I do this? Note that I do not care about what the regex matches, I only care about the way the regex is defined.

Share Improve this question edited Mar 31, 2016 at 8:55 asked Mar 31, 2016 at 8:42 sennett 8,45411 gold badges49 silver badges72 bronze badges

typeof /\.scss$/ is "object" and two objects cannot be pared using equality operators. – Tushar Commented Mar 31, 2016 at 8:53

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2 Answers 2

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Use .toString:

/\.scss$/.toString() === /\.scss$/.toString() // true

It's easier to see what is going on when using the RegExp object:

new RegExp("ab+c").toString() === new RegExp("ab+c").toString() // true

whereas

new RegExp("ab+c") === new RegExp("ab+c") // false

How about using source attribute?

/\.scss$/.source === /\.scss$/.source && /\.scss$/.flags === /\.scss$/.flags

It's faster then using toString function. http://jsperf./source-vs-tostring