Different result from JavaScript RegExp in “rhino1.7.6” vs “V8”

Question

currently, I found the same JavaScript RegExp might generate different result in different JavaScript Engines, here is an example: In Chrome V8 JS engine,

/\x3c/.test("\x3c")  --> returns true

/\x3c/.test(function() {  return "\x3c"  }) -->returns ***false***

In rhino1.7.6,I typed the command like this:

>java -jar js.jar

  Rhino 1.7.6 2015 04 15

js> /\x3c/.test(function() {  return "\x3c"  })

  true

js>

And I tested these two:

/\x3c/.test("\x3c")  --> returns true

/\x3c/.test(function() {  return "\x3c"  }) -->returns ***true***

I am wondering why these two engines generate different result. I believe they must be compliant with some standards.

Please correct me if I am wrong. And moreover, if it is a special occasion, would you please kindly tell me if there are some configurations I can tell JS engine on these special occasions.

Answer 1

Given the value function() { return "\x3c" }

• Chrome converts it to the string "function() { return "\x3c" }", that is, a literal backslash followed by "x3c".

• Rhino converts it to the string "function () { return "<"; }", that is, it reformats the function definition.

Both are actually correct behaviour. The ECMA-262 (a.k.a. Javascript) standard says that String(func) should return "an implementation-dependent String source code representation of func."