For reference, this is the xpcshell impl: 678 Clear(JSContext *cx, uintN argc, jsval *vp) 679 { 680 if (argc > 0 && !JSVAL_IS_PRIMITIVE(JS_ARGV(cx, vp)[0])) { 681 JS_ClearScope(cx, JSVAL_TO_OBJECT(JS_ARGV(cx, vp)[0])); 682 } else { 683 JS_ReportError(cx, "'clear' requires an object"); 684 return JS_FALSE; 685 } 686 JS_SET_RVAL(cx, vp, JSVAL_VOID); 687 return JS_TRUE; 688 } And here's the ipcshell impl: 519 Clear(JSContext *cx, 520 uintN argc, 521 jsval *vp) 522 { 523 jsval *argv = JS_ARGV(cx, vp); 524 if (argc > 0 && !JSVAL_IS_PRIMITIVE(argv[0])) { 525 JS_ClearScope(cx, JSVAL_TO_OBJECT(argv[0])); 526 } else { 527 JS_ReportError(cx, "'clear' requires an object"); 528 return JS_FALSE; 529 } 530 JS_SET_RVAL(cx, vp, JSVAL_VOID); 531 return JS_TRUE; 532 } unfortunately, this is the jsshell impl: 2612 Clear(JSContext *cx, uintN argc, jsval *vp) 2613 { 2614 JSObject *obj; note that if argc == 0, then we do not continue in the if condition: 2615 if (argc != 0 && !JS_ValueToObject(cx, JS_ARGV(cx, vp)[0], &obj)) which means we can't return false: 2616 return JS_FALSE; instead, we use obj which has not been initialized 2617 JS_ClearScope(cx, obj); 2618 JS_SET_RVAL(cx, vp, JSVAL_VOID); 2619 return JS_TRUE; 2620 } At least at beginning of time, clear() didn't say it required any arguments.

Clear was removed.