https://www.graalvm.org/ 
public abstract class com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin extends com.oracle.truffle.js.builtins.GlobalBuiltins$JSFileLoadingOperation
  minor version: 0
  major version: 59
  flags: flags: (0x0421) ACC_PUBLIC, ACC_SUPER, ACC_ABSTRACT
  this_class: com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin
  super_class: com.oracle.truffle.js.builtins.GlobalBuiltins$JSFileLoadingOperation
{
  static final boolean $assertionsDisabled;
    descriptor: Z
    flags: (0x1018) ACC_STATIC, ACC_FINAL, ACC_SYNTHETIC

  static void <clinit>();
    descriptor: ()V
    flags: (0x0008) ACC_STATIC
    Code:
      stack=1, locals=0, args_size=0
         0: .line 50
            ldc Lcom/oracle/truffle/js/builtins/commonjs/CommonJSDirnameGetterBuiltin;
            invokevirtual java.lang.Class.desiredAssertionStatus:()Z
            ifne 1
            iconst_1
            goto 2
      StackMap locals:
      StackMap stack:
         1: iconst_0
      StackMap locals:
      StackMap stack: int
         2: putstatic com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin.$assertionsDisabled:Z
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature

  void <init>(com.oracle.truffle.js.runtime.JSContext, com.oracle.truffle.js.nodes.function.JSBuiltin);
    descriptor: (Lcom/oracle/truffle/js/runtime/JSContext;Lcom/oracle/truffle/js/nodes/function/JSBuiltin;)V
    flags: (0x0000) 
    Code:
      stack=3, locals=3, args_size=3
        start local 0 // com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin this
        start local 1 // com.oracle.truffle.js.runtime.JSContext context
        start local 2 // com.oracle.truffle.js.nodes.function.JSBuiltin builtin
         0: .line 53
            aload 0 /* this */
            aload 1 /* context */
            aload 2 /* builtin */
            invokespecial com.oracle.truffle.js.builtins.GlobalBuiltins$JSFileLoadingOperation.<init>:(Lcom/oracle/truffle/js/runtime/JSContext;Lcom/oracle/truffle/js/nodes/function/JSBuiltin;)V
         1: .line 54
            return
        end local 2 // com.oracle.truffle.js.nodes.function.JSBuiltin builtin
        end local 1 // com.oracle.truffle.js.runtime.JSContext context
        end local 0 // com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    2     0     this  Lcom/oracle/truffle/js/builtins/commonjs/CommonJSDirnameGetterBuiltin;
            0    2     1  context  Lcom/oracle/truffle/js/runtime/JSContext;
            0    2     2  builtin  Lcom/oracle/truffle/js/nodes/function/JSBuiltin;
    MethodParameters:
         Name  Flags
      context  
      builtin  

  protected java.lang.Object getDirName();
    descriptor: ()Ljava/lang/Object;
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin this
         0: .line 58
            aload 0 /* this */
            invokevirtual com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin.getCurrentFolderName:()Ljava/lang/String;
            areturn
        end local 0 // com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/js/builtins/commonjs/CommonJSDirnameGetterBuiltin;
    RuntimeVisibleAnnotations: 
      com.oracle.truffle.api.dsl.Specialization()

  private java.lang.String getCurrentFolderName();
    descriptor: ()Ljava/lang/String;
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=2, locals=3, args_size=1
        start local 0 // com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin this
         0: .line 63
            invokestatic com.oracle.truffle.js.builtins.commonjs.CommonJSResolution.getCurrentFileNameFromStack:()Ljava/lang/String;
            astore 1 /* filePath */
        start local 1 // java.lang.String filePath
         1: .line 64
            aload 1 /* filePath */
            ifnull 6
         2: .line 65
            aload 0 /* this */
            invokevirtual com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin.getContext:()Lcom/oracle/truffle/js/runtime/JSContext;
            invokevirtual com.oracle.truffle.js.runtime.JSContext.getRealm:()Lcom/oracle/truffle/js/runtime/JSRealm;
            invokevirtual com.oracle.truffle.js.runtime.JSRealm.getEnv:()Lcom/oracle/truffle/api/TruffleLanguage$Env;
            aload 1 /* filePath */
            invokevirtual com.oracle.truffle.api.TruffleLanguage$Env.getPublicTruffleFile:(Ljava/lang/String;)Lcom/oracle/truffle/api/TruffleFile;
            astore 2 /* truffleFile */
        start local 2 // com.oracle.truffle.api.TruffleFile truffleFile
         3: .line 66
            getstatic com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin.$assertionsDisabled:Z
            ifne 5
            aload 2 /* truffleFile */
            iconst_0
            anewarray java.nio.file.LinkOption
            invokevirtual com.oracle.truffle.api.TruffleFile.isRegularFile:([Ljava/nio/file/LinkOption;)Z
            ifeq 4
            aload 2 /* truffleFile */
            invokevirtual com.oracle.truffle.api.TruffleFile.getParent:()Lcom/oracle/truffle/api/TruffleFile;
            iconst_0
            anewarray java.nio.file.LinkOption
            invokevirtual com.oracle.truffle.api.TruffleFile.isDirectory:([Ljava/nio/file/LinkOption;)Z
            ifne 5
      StackMap locals: java.lang.String com.oracle.truffle.api.TruffleFile
      StackMap stack:
         4: new java.lang.AssertionError
            dup
            invokespecial java.lang.AssertionError.<init>:()V
            athrow
         5: .line 67
      StackMap locals:
      StackMap stack:
            aload 2 /* truffleFile */
            invokevirtual com.oracle.truffle.api.TruffleFile.getParent:()Lcom/oracle/truffle/api/TruffleFile;
            invokevirtual com.oracle.truffle.api.TruffleFile.normalize:()Lcom/oracle/truffle/api/TruffleFile;
            invokevirtual com.oracle.truffle.api.TruffleFile.toString:()Ljava/lang/String;
            areturn
        end local 2 // com.oracle.truffle.api.TruffleFile truffleFile
         6: .line 69
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            invokevirtual com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin.getContext:()Lcom/oracle/truffle/js/runtime/JSContext;
            invokestatic com.oracle.truffle.js.builtins.commonjs.CommonJSRequireBuiltin.getModuleResolveCurrentWorkingDirectory:(Lcom/oracle/truffle/js/runtime/JSContext;)Lcom/oracle/truffle/api/TruffleFile;
            invokevirtual com.oracle.truffle.api.TruffleFile.getAbsoluteFile:()Lcom/oracle/truffle/api/TruffleFile;
            invokevirtual com.oracle.truffle.api.TruffleFile.toString:()Ljava/lang/String;
            areturn
        end local 1 // java.lang.String filePath
        end local 0 // com.oracle.truffle.js.builtins.commonjs.CommonJSDirnameGetterBuiltin this
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0    7     0         this  Lcom/oracle/truffle/js/builtins/commonjs/CommonJSDirnameGetterBuiltin;
            1    7     1     filePath  Ljava/lang/String;
            3    6     2  truffleFile  Lcom/oracle/truffle/api/TruffleFile;
    RuntimeVisibleAnnotations: 
      com.oracle.truffle.api.CompilerDirectives$TruffleBoundary()
}
SourceFile: "CommonJSDirnameGetterBuiltin.java"
InnerClasses:
  public abstract TruffleBoundary = com.oracle.truffle.api.CompilerDirectives$TruffleBoundary of com.oracle.truffle.api.CompilerDirectives
  public final Env = com.oracle.truffle.api.TruffleLanguage$Env of com.oracle.truffle.api.TruffleLanguage
  public abstract JSFileLoadingOperation = com.oracle.truffle.js.builtins.GlobalBuiltins$JSFileLoadingOperation of com.oracle.truffle.js.builtins.GlobalBuiltins