_Objects/Object/constructor)
    2. [ ` Object.prototype.__proto__ ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto) Deprecated 
  13. Methods 
    1. [ ` Object.prototype.__defineGetter__() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/__defineGetter__) Deprecated 
    2. [ ` Object.prototype.__defineSetter__() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/__defineSetter__) Deprecated 
    3. [ ` Object.prototype.__lookupGetter__() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/__lookupGetter__) Deprecated 
    4. [ ` Object.prototype.__lookupSetter__() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/__lookupSetter__) Deprecated 
    5. [ ` Object.prototype.hasOwnProperty() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwnProperty)
    6. [ ` Object.prototype.isPrototypeOf() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/isPrototypeOf)
    7. [ ` Object.prototype.propertyIsEnumerable() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/propertyIsEnumerable)
    8. [ ` Object.prototype.toLocaleString() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toLocaleString)
    9. [ ` Object.prototype.toString() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toString)
    10. [ ` Object.prototype.valueOf() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/valueOf)

##  In this article

  * Try it 
  * Description 
  * Examples 
  * Specifications 
  * Browser compatibility 
  * See also 

#  RegExp.prototype.unicode

The **` unicode ` ** accessor property of [ ` RegExp ` ](/en-
US/docs/Web/JavaScript/Reference/Global_Objects/RegExp) instances returns
whether or not the ` u ` flag is used with this regular expression.

##  Try it

##  Description

` RegExp.prototype.unicode ` has the value ` true ` if the ` u ` flag was
used; otherwise, ` false ` . The ` u ` flag enables various Unicode-related
features. With the "u" flag:

  * Any [ Unicode code point escapes ](/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Unicode_character_class_escape) ( ` \u{xxxx} ` , ` \p{UnicodePropertyValue} ` ) will be interpreted as such instead of identity escapes. For example ` /\u{61}/u ` matches ` "a" ` , but ` /\u{61}/ ` (without ` u ` flag) matches ` "u".repeat(61) ` , where the ` \u ` is equivalent to a single ` u ` . 
  * Surrogate pairs will be interpreted as whole characters instead of two separate characters. For example, ` /[ð]/u ` would only match ` "ð" ` but not ` "\ud83d" ` . 
  * When [ ` lastIndex ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/lastIndex) is automatically advanced (such as when calling [ ` exec() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/exec) ), unicode regexes advance by Unicode code points instead of UTF-16 code units. 

There are other changes to the parsing behavior that prevent possible syntax
mistakes (which are analogous to [ strict mode ](/en-
US/docs/Web/JavaScript/Reference/Strict_mode) for regex syntax). These
syntaxes are all [ deprecated and only kept for web compatibility ](/en-
US/docs/Web/JavaScript/Reference/Deprecated_and_obsolete_features#regexp) ,
and you should not rely on them.

The set accessor of ` unicode ` is ` undefined ` . You cannot change this
property directly.

###  Unicode-aware mode

When we refer to _Unicode-aware mode_ , we mean the regex has either the ` u `
or the [ ` v ` ](/en-
US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/unicodeSets) flag, in
which case the regex enables Unicode-related features (such as [ Unicode
character class escape ](/en-
US/docs/Web/JavaScript/Reference/Regular_expressions/Unicode_character_class_escape)
) and has much stricter syntax rules. Because ` u ` and ` v ` interpret the
same regex in incompatible ways, using both flags results in a [ ` SyntaxError
` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/SyntaxError) .

Si