Strange-test function of Regular Expression matching

 

In John resig's article about simple inheritance in JavascriptCode:

 
VaR fntest =/XYZ/. Test (function () {xyz ;})? /B _superb /:/.*/;
 

I am confused about the usage of the regular expression matching function test:

 
/XYZ/. Test (function () {xyz ;})
 

I checked the test function description in Mozilla Developer Center:

Executes the search for a match between a regular expression and a specified
String. returns true or false.

Whether the string contains a substring that matches the regular expression. Returns true or false.

Syntax format:

 
Regexp. Test ([STR])
 

Note that the parameter here is a string and it is not mentioned that the parameter of the test function can be a function.

I tried to modify this strange code and got some running results:

/XYZ /. test ("XYZ"); // true/XYZ /. test (function () {"XYZ" ;}); // false/XYZ /. test (function () {return "XYZ";}); // true/XYZ /. test (function () {return XYZ;}); // true/XYZ /. test (function () {return axyz;}); // true/XYZ /. test (function () {return "axyz" ;}); // true/XYZ /. test (function () {return "xayz" ;}); // false
 

What's going on?

Gorgeous split line
========================================================
I finally learned, but the type conversion was originally performed inside test. The following code:

 
/XYZ/. Test (function () {xyz ;});
 

It is equivalent:

 
/XYZ/. Test (function () {xyz;}). tostring ());
 

It is equivalent:

 
/XYZ/. Test ("function () {xyz ;}");
 

So why does the following code return false?

 
/XYZ/. Test (function () {"XYZ ";});
 

After executing this line of code, we will know:

// The execution result of this line of code is: "function () {}" (function () {" XYZ ";}). tostring ();
 

So we can write more weird code to confuse everyone.

 
/Function /. test (function () {}); // true // B indicates the text boundary (for English)/B _superb /. test (function () {This. _ super () ;}); // true