Vilx- Vilx- - 1 month ago 5
Javascript Question

Javascript: what's the point of RegExp.compile()?

I've got a situation where I want to get a regexp from the user and run it against a few thousand input strings. In the manual I found that the

RegExp
object has a
.compile()
method which is used to speed things up ins such cases. But why do I have to pass the regexp string to it again if I already passed them in the constructor? Perhaps constructor does the
compile()
itself?

Answer

The RegExp().compile() method is deprecated. It's basically the same as the constructor, which I assume is why it was deprecated. You should only have to use the constructor nowadays.

In other words, you used to be able to do this:

var regexp = new RegExp("pattern");
regexp.compile("new pattern");

But nowadays it is not any different from simply calling:

var regexp = new RegExp("pattern");
regexp = new RegExp("new pattern");